Tuesday 24 February 2009
Color Sensor
When a primary coloured light ray falls on the system, the glass plate corresponding to that primary colour will allow that specific light to pass through. But the other two glass plates will not allow any light to pass through. Thus only one LDR will get triggered and the gate output corresponding to that LDR will become logic 1 to indicate which colour it is. Similarly, when a secondary coloured light ray falls on the system, the two primary glass plates corres- ponding to the mixed colour will allow that light to pass through while the remaining one will not allow any light ray to pass through it. As a result two of the LDRs get triggered and the gate output corresponding to these will become logic 1 and indicate which colour it is.
When all the LDRs get triggered or remain untriggered, you will observe white and black light indications respectively. Following points may be carefully noted :
1. Potmeters VR1, VR2 and VR3 may be used to adjust the sensitivity of the LDRs.
2. Common ends of the LDRs should be connected to positive supply.
3. Use good quality light filters.
The LDR is mounded in a tube, behind a lens, and aimed at the object. The coloured glass filter should be fixed in front of the LDR as shown in the figure. Make three of that kind and fix them in a suitable case. Adjustments are critical and the gadget performance would depend upon its proper fabrication and use of correct filters as well as light conditions
Color Sensor
When a primary coloured light ray falls on the system, the glass plate corresponding to that primary colour will allow that specific light to pass through. But the other two glass plates will not allow any light to pass through. Thus only one LDR will get triggered and the gate output corresponding to that LDR will become logic 1 to indicate which colour it is. Similarly, when a secondary coloured light ray falls on the system, the two primary glass plates corres- ponding to the mixed colour will allow that light to pass through while the remaining one will not allow any light ray to pass through it. As a result two of the LDRs get triggered and the gate output corresponding to these will become logic 1 and indicate which colour it is.
When all the LDRs get triggered or remain untriggered, you will observe white and black light indications respectively. Following points may be carefully noted :
1. Potmeters VR1, VR2 and VR3 may be used to adjust the sensitivity of the LDRs.
2. Common ends of the LDRs should be connected to positive supply.
3. Use good quality light filters.
The LDR is mounded in a tube, behind a lens, and aimed at the object. The coloured glass filter should be fixed in front of the LDR as shown in the figure. Make three of that kind and fix them in a suitable case. Adjustments are critical and the gadget performance would depend upon its proper fabrication and use of correct filters as well as light conditions
Magnetic proximity sensors
The magnetic proximity switch circuit, in principle, consists of a reed switch at its heart. When a magnet is brought in the vicinity of the sensor (reed switch), it operates and controls the rest of the switching circuit. In place of the reed switch, one may, as well, use a general-purpose electromagnetic reed relay (by making use of the reed switch contacts) as the sensor, if required. These tiny reed relays are easily available as they are widely used in telecom products. The reed switch or relay to be used with this circuit should be the ‘normally open’ type.
When a magnet is brought/placed in the vicinity of the sensor element for a moment, the contacts of the reed switch close to trigger timer IC1 wired in monostable mode. As a consequence its output at pin 3 goes high for a short duration and supplies clock to the clock input (pin 3) of IC2 (CD4013—dual
D-type flip-flop). LED D2 is used as a response indicator.
This CMOS IC2 consists of two independent flip-flops though here only one is used. Note that the flip-flop is wired in toggle mode with data input (pin 5) connected to the Q (pin 2) output. On receipt of clock pulse, the Q output changes from low to high state and due to this the relay driver transistor T1 gets forward-biased. As a result the relay RL1 is energised.
Crystal Oscillator
The design below, for 1 MHz, is a good starting point for a discussion:
CMOS or HCMOS inverter
|\
+--| >0---+----> OUT
| |/ |
| |
+--\/\/\--+
| 1 Mohm |
| |
| \
| / 2.7 kohms
| \
| /
| |
| 1MHz | parallel resonant
+---|[]|--+
_|_ _|_
55pf ___ ___ 60pf
_|_ _|_
\ / \ /
First of all, all crystals have two modes of resonance, the series and parallel resonances. These are closely spaced, and the circuit design must ensure that the resonance mode specified for the crystal is in operation, or you will end up with a frequency different from what is stamped on the crystal.
In the series mode, the crystal shows a low impedance at the resonant frequency. This impedance is on the order of 100 ohms to a few kohms. In the parallel mode, the crystal together with a specified capacitance in parallel, normally 30 pF, shows a high impedance at the resonant frequency. The 30 pF value is used regardless of the frequency.
All crystals have resonances at the odd harmonics, 3, 5, .. times the fundamental (overtones). At frequencies above 25 MHz, crystals are often made to operate at one of the harmonics. In all cases the external circuit must be made to suppress operation at the wrong harmonics or fundamental.
Normally the crystals are specified for the parallel resonance mode. The circuit above is designed for such a crystal. The crystal and the 30 pF parallel capacitor are here transformed into a pi filter network by dividing the 30 pF cap into two 60 pF caps and grounding the middle node. When one end is driven from a low impedance, this network has a 90 deg phase shift at the frequency of maximum gain. With a suitable driving impedance, the phase shift is brought close to 180 degrees. Thus the 2.7 kohm resistor. Other good reasons for it are that harmonics are damped by the resulting RC filter, and that the inverter output is removed from the strange load of the crystal network. A rule of thumb for determining the value of the output to crystal resistor is that it should have the same impedance as the capacitor at the operating frequency:
R:= 1/(2*pi*f*C)
For a 32 kHz oscillator this resistor becomes 160 kohm.
The gain and 180 degrees phase shift of an inverter is now all that is needed to make this circuit oscillate at the right frequency with no twiddling necessary. The resistor between input and output is essential to put the gate in the range of linear operation so the necessary gain to start oscillation will be there. Since a CMOS inverter has very high input impedance, the value can be large. It is not critical, but a low value will increase power dissipation. Use 1000 times the series resistor if you have no other preferences. Note that the inverter *must*not* be a Schmitt trigger. Also note that one of the capacitors is adjusted to correct for the input capacitance of the inverter. In an actual circuit, corrections should also be made for other stray capacitances. The frequency is fine tuned by trimming the capacitors.
At higher frequencies account must be taken to the phase shift of the inverter. The phase shift for a gate when operated as a linear amplifier is certainly not to be found in any data sheet. Just note that 8 ns delay corresponds to 45 degrees phase lag at 16 MHz. Use this type of info as a starting point for adjustment by reducing the R & C:s.
An 4000 series CMOS inverter is usable up to around 5 MHz. Use HC to 25 MHz, AC to 40 MHz. Above that you are into F, ALS or AS families. The same principles apply, but the DC feedback must be arranged by a voltage divider, and the impedance is much lower, on the order of kohms.
To use a 3:rd or 5:th harmonic crystal, you need to insert a bandpass filter into the feedback to avoid oscillating at the fundamental or other harmonic. A series resonant LC filter is something that easily could be inserted between the output and the resistor in the above circuit. Zero degrees phase shift at the center frequency means that the other design criteria still hold. The Q of the filter should be low, around 1-3. Example for 30 MHz: (Just the filter.)
.47 uH 56 pF 180 ohms
from inverter output-----(((((------| |---------\/\/\/-+- to xtal
|
_|_
___ 56 pF
|
_|_
\ /
A C-L-C pi filter and series resonant crystal is another solution:
180 ohms .47uH
from inverter output----\/\/\/--+---(((((----- xtal --+-- to input
| series |
_|_ _|_
___ 120pF ___ 100pF
| |
_|_ _|_
\ / \ /
Component values should not be taken literally. (No indication of inverter type given!)
Some additional hints:
Don't distribute the inverter output node over a large PC board. Instead use free inverters of the same chip for buffering.
If you use the other inverters of the same chip for other signals, be aware that there is crosstalk that causes phase jitter in the oscillator output that might be disturbing in critical applications. For a clean noise-free output, a local voltage regulator to supply the inverter is also a good idea.
Also apply care in the PC board layout of the oscillator. Ground plane, good power decoupling, no signal wires routed under the crystal circuit.
Info on CO2 lasers wanted (ho hum)
Wouter Slegers
(wouter@stack.urc.tue.nl)
Supreme 7 (S7) Productions proudly present....
Palm Beach BB Uk - (0303) 265979
LASER WEAPONRY / PART 1 / LASER SIGHTS
by The Deceptor and Flip
WELCOME!.....To part 1 of LASER WEAPONRY - to be included in each issue of ELEKTRIX. This first tutorial deals with building your own laser sights as seen in films such as 'THE TERMINATOR' and actually used by US military and UK M.O.D. for such weapons as ANTI-TANK GUNS, APRLs and other high- power military weapons. The type of sights mentioned here can be strapped onto the barrel/tube and provide perfect targetting - also phreaks people out if you walk down the street pointing the beam at people.
NOTES:
* The laser used is a helium-neon one which emits a bright red beam.
* Pointing it in someone's eyes will probably blind them so be careful with where you point it - unless ofcourse you intend to do damage (?!)
* It can't burn skin or paper or anything - it's only really useful in this case as laser sights - although in future issues I others will explain how you can use it for Data Snooping.
* Total project cost is about 40 quid.
WHAT YOU NEED:
* A Helium-Neon laser tube.
* A portable power supply (easily transformed into a backpack).
A fairly decent tube can be obtained from BULL ELECTRICAL for about 25 quid
J&N BULL ELECTRICAL
250 PORTLAND ROAD
HOVE, BRIGHTON
SUSSEX BN3 5QT
The specs. of the JN BULL tube are as follows:
Maker: Philips (holland) - could buy cheaper direct I guess.
makers ref.no: LHN-VLP/04
type: Helium-Neon
Size: approx 260mm x 40mm
Striking voltage: 6-8KV
Running voltage: 1.2-1.5KV
Output: 1.6mW (not bad at ALL! - usual MAX is around 2mW!!!)
Running current: 5mA
Polarity: white lead = negative, black lead = positive
Estimated life: 5000 hours
Warm-up time: 1 second
Wave length .63+0.01um (62.8nm roughly - red part of spectrum)
Although the light emitted is actually red you'll only see the actual beam if the air is misty or dusty...though the spot at the end of the beam is perfect - the invisible beam is an advantage though if you don't want to be detected.
I've included that info in case you pickup the beam as surplus stock some- where without the info. The tube isn't too fragile either - I dropped mine from two foot once - nothing.
As you're going to need a power supply that's portable then you'll be hard pressed to find a company that does one....so here's the docs.
Part 1:
~~~~~~~ C4-C10 - DISK CERAMICS
1M-1Watt
R3 100p 100p 100p 100p
----====----||---------||--------||--------||-------
D3-D11: | C4 /\ C6 /\ C8 /\ C10 / |
high- | Diodes follow / \ / \ / \ / |
voltage | direction to D5 D6 D7 D8 D9 D10 D11 |
3kV diodes| D11 from D5 / \ / \ / \ / | |R4
A | / C5 \/ C7 \/ C9 \ / | |47K
<--------------|------D3>|--------||--------||--------||----- |
_ | | 100p 100p 100p | |R5
Diode /|\ D4 | | |33K
going | | C2===0.1/1.6KV |
up.....> | | | ____|
B | | +VE -_|_
/_____________/|\____________| | |
\ | | | | LASER
| | | | TUBE
<--To part 2 | C3===0.1/1.6KV |___|
| | GND - |
| | |
| | |
|_____________|_________________________________|
________________________________ | /\|| Part2: | \/|| ~~~~~~ | R1 /\|| | ______----______________\/|| ----- <- From Part 1 | | ---- ____|____ ||/\ (A) | | 110 2W / | /\||\/ | | ______/ | | \/||/\ <--Ferrite core | | / R2|_|1K/\||\/ transformer | |_____|/ / __\/||/\ DU 1n4002 100v | DU |\X C1 |------|__ ||\/ Going: UPWARDS | __|_______|___)|_| \ /\|| ----- <- From Part 1 | | DD | )| | \/|| (B) DN 1n4002 100v |__/___|_____|/X 10uf | /\|| Going: DOWNWARDS \ |\______________\__\/|| | / | | | | | \ - Switch X - Collector | | | | Transistors are: | ===== D4005 NPNs | --- 12V of AA NICADS in series | ===== (BATTERY) | --- (11x1.2V is sometimes a | | little more reliable) | | -------------------------
I hope people understand those schematics - TXT files make life so hard!...
If you can't understand something then contacts us at Palm Beach and we'll send u a photocopy of our own docs if you like (fax optional).
Use:
Strap the tube (maybe put it in a protective casing too) to the barrel/tube and then FIRE AWAY!!!!
If you point it at someones eyes or your own then you/they can say goodbye to them for good.
Phun with your tube:
As well as being GR8 for sights you can use it for other things:
* Shine it at a neighbours window while they're sleeping and the room will fill with a eerie red light!! haha - gr8....and this can be done from a few hundred feet with excellant results.....
* Another good use is to point it just in front of someones feet while they are walking....The red dot on the ground will make them REAL paranoid!
* Picking up conversations in buildings by bouncing the beam off a window and via modulation of the beam and conversion at the opposite end you can hear very high quality conversations without being seen or heard - this is a bit more tricky though....details in the next ELEKTRIX issue.
* PLAIN TERROR! YERRRRR! PHUCK this is the bit I love.....walk down the road real casual or through a town centre....carrying your nice laser....aiming the beam at people as they go by....This really phreaks them out...best if you and a m8 piss about and make out he's gone blind. People will run fer their lives - you need to add a nice buzz noise to it - that really makes it seem quite an awesome device!
That's it for this LASER WEAPONRY issue.....a great addition for any launcher ,tube, rifle, or just about any direct beam weapon......It could also be a fantastic sight for a carbon dioxide laser (needed since CO2 lasers are not at all visible - phun).....YUP! CO2 laser is in Part 2 of LASER WEAPONRY... fully portable and with over 200W output we are talking *** SERIOUS POWER ***
Frequency and Capacitance meter
Circuit will look something like:
+5 ---+---------------+---+
| | |
R +----------+
|(see below) | 8 4 |
+---+------+-----|7 3|------/\/\/\---+------- Vout
: | | LMC555 | |
C to test +-----|6 | -----
: | | -----
ground +-----|2 5|----+ |
| | 1 | | ground
| +----------+ 0.1 uF
| | |
Clock ----+ ground ground
^
(see | next section - CMOS Oscillator)
The ON time for the monostable is about 1.1RC, so component values that should work would be a 50 Hz clock, say a 1 Hz low-pass filter on the output, and R = 9.09K, 1%. That combination will give an output of one volt per microfarad. Switch R in decades for smaller capacitors. Trim R for calibration.
Quiz-Show Indicator
SW3
+6V -o_|_o----+----------+----------->>--------+----------+----->>
| | | |
LAMP1 | | LAMP2
| | SW1 | SW2 |
+--A> |o| ==| --B> | |== ----- |o | | o| -----
SCR1 \ / | | | | \ / SCR2
\ / R3 ^ ^ R4 \ /
----- | CR1 CR2 | -----
| \ | | | | / |
| +--R2--+---+ +---+--R5--+ |
| | | |
| R1 R6 |
| | | |
GND ----------+---+----------------->>----------------+---+--->>
SW1,SW2 normally open momentary pushbuttons
SW3 normally closed momentary pushbutton
LAMP1, LAMP2 6V incandescent lamps
R1, R6 470 ohm
R2,R3,R4,R5 1 K
SCR1, SCR2 Small SCRs, not power type
CR1, CR2 1N914 diodes
+ connection
^ cathode of a diode
--A>--B>
Circuit Description
When the circuit is first powered up (or after a reset -- same thing), both SCR gates are held at ground potential by R1 and R6. Therefore, neither SCR will latch up, and both lamps will be off.
When one of SW1 or SW2 is pressed, the corresponding SCR's gate is pulled high, so the SCR latches on. Even if the switch is released, the SCR remains latched, keeping the lamp illuminated.
Diodes CR1 and CR2 ensure that only one lamp may be on at a time. Once an SCR turns on, it forces the other SCR's gate to remain at a low voltage, even if its switch is pressed.
It is probably possible to change the bulbs and the power supply to 12V with no other circuit changes, but I have only built a 6V system. The circuit does not draw current when the lamps are off, so it may be battery powered with no additional cutoff switch. I built the whole thing in a plastic shoebox.
Serving Suggestion: These are great fun in elementary school classes, and as the whole thing can be built for about $5, it's well worth letting the kids have fun while they destroy it!
Headlight Reminder Circuit
A [...] solution is to go from the +12 Switched sidelight feed, via a buzzer to the drivers door light switch, you then need to put a diode in the door circuit to stop the other doors operating the buzzer.
+12v (sidelights)
|
+-+--+
| | Buzzer (12v)
+-+--+
|
+-------|<|-------- To existing drivers interior light switch
| Diode
|
O
----| Drivers door switch
O
|
Car Chassis
Thus when you leave your lights on AND open the drivers door, the buzzer sounds. If you mean to leave your lights on, just shut the door and the buzzer stops!
Connectors: D25 male
Resistors: 640k,320k,160k,80k,40k,20k,10k,5k,390 (+-1%)
(You can use different values of resistors, but the ratio of the values of the resistors must be same. 0.5, 1, 2, 4, 8, 16, 32, 64 etc.) 1, 2, 4, 8, 16, 32, 64, 128
Capacitor: Electrolytic or solid Tantalum 10 uF 10V
SCHEMATIC
+---+
| 2 | ---<640k>---+
| 3 | ---<320k>---+
| 4 | ---<160k>---+
| 5 | ---<80k>----+
| 6 | ---<40k>----+
| 7 | ---<20k>----+-----+---- 10 uF -------> Out
| 8 | ---<10k>----+ |
| 9 | ---<5k>-----+ <390>
| | |
| 25| ------------------+------------------+
+---+ |
===
Ground
How to build
Solder all D25 male connector pins to corresponding D25 female connector pins (pin 1 to pin 1 etc) Connect the resistors according the chematic. It is maybe not possible to obtain exact resistor values. If you can't obtain them, try nearest values. <1%>
How to use
Connect this circuit to the centronics printer port of your IBM PC or compatible. Connect the printer cable to the D25 female connector of the circuit. Your printer should work correctly with this circuit and you can keed this circuit connected all the time. Connect the sound output to your stereo system. Line in and mic lines are suitable because the output level of this circuit is adjustable (about 0-2V PP). The sound quality is very good.
Headlight Reminder Circuit
A [...] solution is to go from the +12 Switched sidelight feed, via a buzzer to the drivers door light switch, you then need to put a diode in the door circuit to stop the other doors operating the buzzer.
+12v (sidelights)
|
+-+--+
| | Buzzer (12v)
+-+--+
|
+-------|<|-------- To existing drivers interior light switch
| Diode
|
O
----| Drivers door switch
O
|
Car Chassis
Thus when you leave your lights on AND open the drivers door, the buzzer sounds. If you mean to leave your lights on, just shut the door and the buzzer stops!
Connectors: D25 male
Resistors: 640k,320k,160k,80k,40k,20k,10k,5k,390 (+-1%)
(You can use different values of resistors, but the ratio of the values of the resistors must be same. 0.5, 1, 2, 4, 8, 16, 32, 64 etc.) 1, 2, 4, 8, 16, 32, 64, 128
Capacitor: Electrolytic or solid Tantalum 10 uF 10V
SCHEMATIC
+---+
| 2 | ---<640k>---+
| 3 | ---<320k>---+
| 4 | ---<160k>---+
| 5 | ---<80k>----+
| 6 | ---<40k>----+
| 7 | ---<20k>----+-----+---- 10 uF -------> Out
| 8 | ---<10k>----+ |
| 9 | ---<5k>-----+ <390>
| | |
| 25| ------------------+------------------+
+---+ |
===
Ground
How to build
Solder all D25 male connector pins to corresponding D25 female connector pins (pin 1 to pin 1 etc) Connect the resistors according the chematic. It is maybe not possible to obtain exact resistor values. If you can't obtain them, try nearest values. <1%>
How to use
Connect this circuit to the centronics printer port of your IBM PC or compatible. Connect the printer cable to the D25 female connector of the circuit. Your printer should work correctly with this circuit and you can keed this circuit connected all the time. Connect the sound output to your stereo system. Line in and mic lines are suitable because the output level of this circuit is adjustable (about 0-2V PP). The sound quality is very good.
Stepper motor controller
Description.
Here is the circuit diagram of a simple stepper motor controller using only elementary parts.The circuit uses , four transistor (SL100) to drive the motor windings , two NOT gates and one XOR gate to decode the two bit control logic to drive the four windings of the motor.The diodes D1 to D4 protects the corresponding transistors from transients generated during the switching of motor windings. d0 and d1 are the control logics which determines the direction of rotation as well as speed.
Circuit diagram with Parts list.
Notes.
- The control logic for the circuit can be obtained from a 2 bit up/down counter clocked by a 555 astable multivibrator.The direction of count determines the direction of rotation and the frequency of astable multivibrator determines the speed of rotation.
- IC1a IC1b belongs to same IC 7404.
- Pin 14 and pin 7 of both IC1 and IC2 must be connected to +5 V and ground respectively,though it is not shown in circuit diagram.
- The 5V can be obtained from a 7805 based power supply circuit
- 5V power supply using IC 7805.Click Here.
- Vcc is the voltage required for the stepper motor.It varies from motor to motor.Here we can use up to 24V stepper motors.For higher operating voltages and power the SL100 transistors must be replaced with higher power transistors like 2N3055.
Truth table for clockwise rotation.
Temperature controlled DC fan
Description.
Here is a simple circuit based on two transistors that can be used to control the speed of a 12 V DC fan depending on the temperature.A thermistor (R1) is used to sense the temperature. When the temperature increases the base current of Q1 (BC 547) increases which in turn decreases the collector voltage of the same transistor. Since the collector of Q1 is coupled to the base of Q2 (BD 140), the decrease in collector voltage of Q1 forward biases the Q2 more and so do the speed of the motor. Also, the brightness of the LED will be proportional to the speed of the motor.
Circuit diagram with Parts list.
Notes.
- The R1 can be a 15K @ 20°C ,N.T.C thermistor.
- The M1 can be a 12V,700mA fan motor.
- The capacitor C1 must be rated 25V.
- The circuit can be powered from a 12V PP3 battery or 12V DC power supply.
- Assemble the circuit on a good quality PCB or common board.
Friday 20 February 2009
Automatic Loudness Control
Parts:
P1_________________10K Linear Potentiometer (Dual-gang for stereo)
R1,R6,R8__________100K 1/4W Resistors
R2_________________27K 1/4W Resistor
R3,R5_______________1K 1/4W Resistors
R4__________________1M 1/4W Resistor
R7_________________20K 1/2W Trimmer Cermet
C1________________100nF 63V Polyester Capacitor
C2_________________47nF 63V Polyester Capacitor
C3________________470nF 63V Polyester Capacitor
C4_________________15nF 63V Polyester Capacitor
C5,C9_______________1΅F 63V Electrolytic or Polyester Capacitors
C6,C8______________47΅F 63V Electrolytic Capacitors
C7________________100pF 63V Ceramic Capacitor
IC1_______________TL072 Dual BIFET Op-Amp
SW1________________DPDT Switch (four poles for stereo)
Comments:
In order to obtain a good audio reproduction at different listening levels, a different tone-controls setting should be necessary to suit the well known behaviour of the human ear. In fact, the human ear sensitivity varies in a non-linear manner through the entire audible frequency band, as shown by Fletcher-Munson curves.
A simple approach to this problem can be done inserting a circuit in the preamplifier stage, capable of varying automatically the frequency response of the entire audio chain in respect to the position of the control knob, in order to keep ideal listening conditions under different listening levels.
Fortunately, the human ear is not too critical, so a rather simple circuit can provide a satisfactory performance through a 40dB range.
The circuit is shown with SW1 in the "Control-flat" position, i.e. without the Automatic Loudness Control. In this position the circuit acts as a linear preamplifier stage, with the voltage gain set by means of Trimmer R7.
Switching SW1 in the other position the circuit becomes an Automatic Loudness Control and its frequency response varies in respect to the position of the control knob by the amount shown in the table below.
C1 boosts the low frequencies and C4 boosts the higher ones. Maximum boost at low frequencies is limited by R2; R5 do the same at high frequencies.
Technical data:
Frequency response referred to 1KHz and different control knob positions:
Total harmonic distortion at all frequencies and 1V RMS output: <>
Notes:
-
SW1 is shown in "Control flat" position.
-
Schematic shows left channel only, therefore for stereo operation all parts must be doubled except IC1, C6 and C8.
-
Numbers in parentheses show IC1 right channel pin connections.
-
R7 should be set to obtain maximum undistorted output power from the amplifier with a standard music programme source and P1 rotated fully clockwise.
Amplifier 2x30W with STK465
Note: The text is AUTO translated from Greek version
A amplifier of acoustic frequencies can be manufactured with discernible materials, despite is known so much the difficulties of finding of materials, what the problem of regulations. These difficulties are overcome relatively easily if we find amplifier in form completed.
Completed STK465 is an amplifier of acoustic frequencies that offers qualitative output, using minimal exterior elements. Substantially he is one of big completed force. Has a line pins and incorporated metal surface for adaptation in cooler. The provision pins in a line, facilitates the placement completed in the end printed and his support in cooler. The circuit functions in a big range of benefits of catering, from 20V as 60V, and it attributes 30WRMS, when the tendency of catering is above 50V and composer resistance of loudspeaker is the 4 or 8 Ohm. The catering should be symmetrically.
When it functions with tendency 56V then the tendency will be ± 28V as for the ground. With this recommended tendency of catering, the attributed force is 30 WRMS in charge 8W. The price of deformity is acceptable and oscillates around in the 0,08% for force of expense from 1W until 30W. Curve response his it is extended from 10Hz and reaches 100 KHz, with divergence 0dB and -3dB respectively, measured in force 1W. Using evolved techniques, completed amplifier STK465, can minimise the deformities even in highest levels of force. Other characteristically that determines the completed circuit they are: the wide area and the high aid.
Schematic
STK465 is drawn to be constant, when it functions in conjunction closed bronchi with big gain. As all the amplifiers, thus and this, under certain unfavourable conditions, can turn in oscillations. These oscillations have as result of returning in the same phase from the exit in the entry, or from bad designing PCB, or from bad choice of corridors in the circuits of entry. When you draw a printed circuit, it is important to return the current of charge and the current of signal of entry in the ground, via different corridors. Generally, positive is the charge it is connected directly in pin the catering and in particular in common pin electrolytic the catering. If entry and charge are connected directly in the 0V via the same road, then are created retroactions, what have as consequence oscillations and the deformity. To you we propose maintaining as much as possible smaller the cables of ground 0V and the capacitors of unharnessing, so that are limited the results of self-induction and resistance of lines of copper PCB. Sometimes the oscillation is owed in big length drivers between entry and expense, particularly if these have big length and the complex resistance of source are high. Can anticipate the oscillation that is owed in long wirings, adding capacitor from 50 - 500pf between pins entry. For the low deformity, important role plays also the placement of conductors of catering. This should be kept as much as possible more far from the wiring of entry, so that is deterred thus the not linear catering in the entry of IC. STK 465 does not have system of thermal protection, so that are avoided the thermal elations. If the temperature of JC reaches in high price, then the amplifier changes the polarisation of rung of expense. If the temperature is increased, then in order to is ensured the operation it should you grow cooler. The amplifier functions with catering of double polarity. In form 1 we see the electronic circuit of amplifier that Is based on the STK 465.
The circuit is stereo and has two channels of amplifier in a nutshell. It is a formal designing that develops positively all the particularities completing. Concretely, we observe that the not inverting entry completed (pins 2 and 15, for each channel), is supplied from divider of tendency, which ensures tendency from the tendency of expense completing. At the same time with the entry in each channel, exists a capacitor 470rF, which achieves the unharnessing, in that it concerns the AC components of high frequency, while en line a capacitor 1mF allows in the amplifier to be supplied from desirable flourish acoustic frequencies, fence simultaneous the continuous component. Bronchi unharnessing it is realised with the help of networking of two resistances 33KW and 330W and a capacitor 100mF, which finally ensures factor of aid equal with 100. Finally, at the same time with the exit exists networking RC (0,1mF - 4,7 Ohm) that it attends to the minimisation of phenomenon crossover. The amplifier can be supplied from a line of double polarity. Still it can function under a wide region of tendencies (±10V as ±28V). The requirements of current depend from the force of expense and it can they begin from 120mA up to 1A. It is very important the catering to be sufficiently unharnessing, so that is avoided imports of annoying noises.
The manufacture
For the realisation of manufacture you are consulted the forms 2 and 3 that portray the PCB and placement of materials in this. Does not exist a dangerous element in the manufacture that it should him you are careful particularly, so much at the soldering, what at the use. Be careful the electrolytic capacitors, the placement cooler completed and naturally the polarity of lines of catering. One still directive in what it concerns the catering: good it is it is used power supply with big capacitors standardisation or still better stabilised.
Parts
R1 = 1K | C1 = 1uF/35V |
R2 = 3,3K | C2 = 470pF |
R3 = 100 | C3 = 100uF/60V |
R4 = 330 | C4 = 100uF/60V |
R5 = 3,3K | C5 = 10uF/60V |
R6 = 1K | C6 = 47uF/60V |
R7 = 0,33 | C7 = 8,2pF |
R8 = 33Κ | C8 = 0,1uF |
R9 = 4,7 | C9 = 1uF/35V |
R10 = 1Κ | C10 = 470pF |
R11 = 3,3Κ | C11 = 100uF/60V |
R12 = 100 | C12 = 100uF/60V |
R13 = 330 | C13 = 10uF/60V |
R14 = 3,3Κ | C14 = 47uF/60V |
R15 = 1Κ | C15 = 8,2pF |
R16 = 0,33 | C16 = 0,1uF |
R17 = 33Κ |
|
R18 = 4,7 |
|
|
|
IC1 = STK465 | |
LS1 = Speaker 40W 8 or 4 Ohm |
Digital Volume Control
With the manufacture that to you we propose you can make a active filter in order to you lead a loudspeaker of very low frequencies. With this you will place one bigger speaker between the HIFI speakers of you. In order to you have a complete picture of sound you will need also the corresponding amplifier. In the entry of circuit you will connect the two exits of preamplifier or the exit of line of some preamplifier. The circuit of manufacture allocates a exit in order to is led means of circuit of force subwoofer. If for some reason you do not have space in order to you place the third speaker in space of hearing, then you can select smaller speaker. The output will depend from the type of music that you hear. If in deed you have space, then after you make a filter and remain thanked, you can him recommend in your friends or still make other same for your friends.
Theoretical circuit
In the form it appears the theoretical circuit of filter. In first glance we see three different circuits that are mainly manufactured round two operational amplifiers. This circuits constitute mixed, amplifier with variable aid and a variable filter. The manufacture end needs a circuit of catering with operational tendency of catering equal with ±12. the operational amplifiers that constitute the active elements for this circuits of are double operational type as the TL082 and NE5532. The operational these amplifiers belong in a family provided with transistor of effect of field IFET in their entries. Each member of family allocates in their circuit bipolar transistor and effect of field. This circuits can function in his high tendency, because that they use transistor of high tendency. Also they have high honor of rhythm of elevation (slew rate), low current of polarization for the entries and are influenced little by the temperature. The operational these amplifiers have breadth of area unity gain bandwidth 3MHz. A other important element for their choice is the big reject of noise, when this exists in the line of catering.
The price of reject is bigger than 80dB, their consumption is small, from 11 until 3 mA. They are internally sold in nutshell with eight pins and allocate two operational amplifiers, In the same line in nutshell 14 pins they incorporate four operational, In the trade they are sold with code TL074, TL084 and TL064, In nutshell with eight pins they are sold operational amplifiers TL061 TL071 kajTL081. In the manufacture we used the TL082 that has two operational. First operational from the TL082 it works as amplifier and mixed for the two channels, In his negative entry he exists one small mixed with two resistances. A potentiometer in this rung determines the aid of circuit. In the point this left winger and the right channel of preamplifier they are added means of two resistances. En continuity the operational strengthens signal with aid made dependent from the price that has the potentiometer.
The place of runner is proportional with the aid of circuit. The second operational amplifier is the filter of manufacture. The filter of is acoustic frequency of second class and he is made with the materials that are round the operational amplifier. The filter of is low passage with variable frequency of cutting off. This frequency can be altered and take prices from very low frequency the 30Hz or still exceed 150Hz. The frequency of cutting off of filter depends from the prices that have the elements of circuit. Altering the values of elements we can have frequency of cutting off 150Iz, 130Iz, J00Iz, 7Ïz, 6Íz even 3Íz, this prices they can be achieved with the simple rotation of double potentiometer. The circuit of filter has been made around one operational' that it has completed TL082 that is double operational amplifier. In the exit of filter we will link the plug of expense where is connected the amplifier. In the exit of circuit is presented, the limited as for the breadth of frequencies, signal that we apply in the entry of circuit.
Manufacture
Parts
R1 = 39 Kohm | R2 = 39 Kohm |
R3 = 47 Kohm | R4 = 10 Ohm |
R5 = 22 Kohm | R6 = 4,7 Kohm |
R7 = 22 Kohm | R8 = 4,7 Kohm |
R9 = 10 Ohm | R10 = 220 Ohm |
C1 = 39 pF | C2 = 0.1 uF |
C3 = 0.1 uF | C4 = 0.2 uF |
C5 = 0.4 uF | C6 = 0.1 uF |
C7 = 0.1 uF | IC1 = TL064 |
In order to you make the manufacture you will need printed that appears in the form. In this you will place the materials according to the following form. The materials are enough also easy can become certain errors. With few attention however you can him avoid. If they are presented difference malfunctions, you check carefully the circuit. The circuit, as we said, is filter and it should they are used materially good precision and quality, particularly for the capacitors. The capacitors of filters will have tolerance 5%. Of course, the manufacture will also work with material of lower quality, the trial of manufacture can become with acoustic signal of generator We apply the generator in the entry of manufacture and we measure with a voltmeter the tendency in the exit of filter. If we alter the potentiometer and are altered the tendency, then all have well.
100W RMS Amplifier
Circuit Description:
This is a 100 watt basic power amp that was designed to be (relatively) easy to build at a reasonable cost. It has better performance (read: musical quality) than the standard STK module amps that are used in practically every mass market stereo receiver manufactured today. When I originally built this thing, it was because I needed a 100 WPC amp and didn't want to spend any money. So I designed around parts I had in the shop.
The design is pretty much a standard one, and I'm sure there are commercial units out there that are similar. To my knowlwdge, it is not an exact copy of any commercial unit, nor am I aware of any patents on the topology. To experienced builders: I realize that many improvements and refinements can be made, but the idea was to keep it simple, and should be do-able by anyone who can make a circuit board and has the patience not to do a sloppy job.
The input stage is an LF351 op amp which provides most of the open loop gain as well as stabilizes the quiescent dc voltage. This feeds a level shift stage which references the voltage swing to the (-) rail. The transconductance stage is a darlington, to improve high-frerqency linearity. The 2SC2344 by itself has a rather large collector-base capacitance which is voltage dependent. The MPSA42 presents this with a low-z and has a C(ob) of only a few pf that is effectively swamped by the 33pF pole-splitting cap. The stage is supplied by the 2SA1011 active load (current source) which is about 20 ma. The current to the stage is limited by the 2N3094 to about 70 ma under worst case.
The output is a full complementary darlington with paralleled outputs. Although you could "get away with" only one if only 8 ohm easy-to-drive loads are used, this is not recommended. The use of parallel devices increases the ability to drive reactive loads (which can pull a significant current while the voltage waveform crosses zero and puts a high voltage and a high curent across the transistor simultaneously), gives the amp a higher damping factor, and reduces the maximum current each transistor has to supply to peaks (remember, the gain of a power transistor drops as the current increases).
Compensation is two-pole and one zero. The op-amp's pole and the pole generated by the 33pf cap and the 470 ohm bias resistor of the MPSA42 dominate. (the 33pF gets multiplied by the stage gain.) The 22 pf feedback capacitor provides lead compensation, and is taken from the output of the tranconductance stage rather than the output itself. In this way, the phase lag introduced by the output transistors is not seen by the high-frequency feedback. This intorduces a closed-loop pole which limits the high-frequency response. The two compensation capacitors must be type 1 creamic (NPO) or silver mica - with ZERO voltage coefficient.
The amp was designed to run 2 channels off a +/- 55 volt unregulated supply, reducing to +/- 48 volts under full load. It used a 40-0-40 volt, 5 amp toroid transformer, a bridge rectifier, and 10,000 uf of filter cap per side. If a standard EI transformer is used, a 6-amp rated unit should be used. With this power supply, it produces 100 watts continuous, both channels driven into 8 ohms resistive with no clipping. Dynamic headroom is about a db and a half. For more headroom, unloaded voltages to +/- 62 volts can be used with no circuit modification.
By the way, the schematic is in Postscript.
Limitations:
With no modifications the amp will drive 4-ohm speaker systems with no current limiting. The short-circuit current limit is set to about 4.5 amps peak, which will handle conventional speaker loads.(It will, of course, produce higher peak currents as the output voltage swing approaches the rail.) If you are going to be running some of those high-end speakers with impedance minima of half an ohm, or that stay reactive throughout most of the audio band ( ie, 0.5 +j3.2 ohms) you will probably already own a better amp than this. If the higher-power Motorola power transistors are used, it will drive a 2-ohm resistive load without problems (except heat).
I have never heard any slew-induced distortion on this amp with a CD player's band-limited (22KHz) signal. I suppose that real high-end freaks could pick it to pieces by hitting it with a TTL square wave mixed with a 19KHz stereo pilot tone and crank it up. I guarantee that there will be spurs all over the spectrum, but who listens to that?
Possible Modifications: (What if I want mo' power???)
The Toshiba output transistors (2SD424/2SB554 pair) shoud not be used with supply voltages above +/-60 volts. If you plan on cranking it up, use more in parallel or use the 250 watt Motorola pairs (MJ15024/MJ15025). If very low impedances are expected, raise the bias in the transconductance stage to give more base drive to the output darlingtons or add another current gain stage. Higher-Beta (and faster) power transistors can't handle reactive loads worth a crap. Don't substitute high-fT parts unless you are sure they have adequate second-breakdown capability.
The NE5532 op-amp can be used in the input stage. If more than one are used off the +/-15 volt shunt regulators (balanced ins, anti-slew Bessel filters, etc.) the 2.7K dropping resistors may need to be reduced to say, 1.8K ohm to maintain regulation. The 2.7K resistors will allow up to 4 LF351 type op amps off the regulator (I used a quad 347 for balanced inputs to avoid hum in a DJ setup).
Construction tips:
The output transistors and thermal compensator (2SC1567) will need to be mounted on a common heat sink - a finned unit measuring 5 in. high by 8 in. wide with 1.25 in fins should do nicely for one channel. (They look nice if you make the sides of the case out of them). Most normal applications won't require more cooling than this. The reason the 2SC1567 was chosen for the output bias regulator is because it is fully insulated - the ECG version will require additional mounting hardware. TO-3 hardware for the outputs is cheap and easy to get.
The driver transistors and voltage amps (2SC3344/2SA1011 pairs) will all require heatsinking as well. Individual TO-220 heat sinks on the circuit board will suffice - the voltage amps dissipate about 1.4 watts each. A common piece of 1/8 in. thick 1 in. wide X 4in. long angle aluminum will suffice for all 4 on each channel, but bear in mind that it must be oriented to take advantage of natural convection, and the transistors must be insualted.
Keep the imput grounds separate from everything else, and return them at ONE point. Failure to do so WILL result in high distortion (5% or so), or even oscillation.
The output stage bias should be set to about 25 milliamps in the output transistors. This value takes a while to stabilize, and you may have to monitor it over an hour or so during initial setup. To measure it, measure the voltage across the emitter resistor and use Ohm's law. This way, you can check the current sharing in the parallel output transistors at the same time and change them if there is a serious discrepancy. With parts of the same date code, they should not be off by more than 10% after it has warmed up. Higher output stage biases can be used, but it takes more care in setting it. If you want an idle current of more than 50 milliamps per side, increase the value of the emitter resistors.
Initial Checkout:
DO NOT just plug something like this in! A seemingly insignificant error can set your house on fire! (As well as blow out $30 worth of transistors in a microsecond.) A variac will work in theory, but the amp may latch to the rail if the supply drops too low. I suggest the use of a ballast resistor - a 60 to 100 watt light bulb in series with the AC mains. You get a bright flash when the caps charge, and then it goes (almost) out as the idling supply current reaches its nominal low value. The amplifier will then work normally at low volumes. If the amp draws too much current for whatever reason, the lightbulb will glow brightly, increase resistance, and limit the power to the circuit. Usually, there will either be a mis-wire (use your DMM) or oscillation (will show up on a scope or RF power measuring device). If the bulb goes dim-bright-dim-bright... then the amp is marginally stable and the grounding layout should be checked. Compensation capacitor values may need to be adjusted if any significant changes were made. Mine is stable the way it is.
Additional Notes:
The schematic is in postcript, so it should just be able to be printed out. The emitters of the transistors are labelled by an "e". I was too lazy to put arrows on the transistor symbols - and I've been using it that way for over a year now.
Trouble finding parts? MCM (1-800-543-4330) has all the transistors. Total cost for a stereo version should be between $150 and $250, depending on what kind of bargains you can find on the case, transformer, and heatsinks. If you have to pay "list" for everything, it will likely cost about $1000 to build.
The information included herin is provided as-is, with no warranties express or implied. No resposibility on the part of the author is assumed for the technical accuracy of the information given herein or the use or mis-use of said information.
The equipment described in this article was designed, fabricated, and tested on my own personal time using my own personal resources.
Click HERE to get the postscript circuit diagram.
Click HERE to get the pdf circuit diagram50 Watt Amplifier
This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.
Schematic
Parts
Part | Total Qty. | Description |
R1 | 1 | 200 Ohm 1/4 W Resistor |
R2 | 1 | 200K 1/4 W Resistor |
R3 | 1 | 30K 1/4 W Resistor |
R5 | 1 | 1K 1/4 W Resistor |
R6 | 1 | 5K 1/4 W Resistor |
R7,R10 | 2 | 1 Meg (5%) 1/2 W Resistor |
R8,R9 | 2 | 0.4 Ohm 5 W Resistor |
R11 | 1 | 10K Pot |
R12,R13 | 2 | 51K 1/4 W Resistor |
R14 | 1 | 47K 1/4 W Resistor |
C1 | 1 | 100uF 35V Electrolytic Capacitor |
C2 | 1 | 0.011uF Capacitor |
C3 | 1 | 3750pF Capacitor |
C4,C6 | 2 | 1000pF Capacitor |
C5,C7,C8 | 3 | 0.001uF Capacitor |
C9 | 1 | 50pF Capacitor |
C10 | 1 | 0.3uF Capacitor |
C11,C12 | 2 | 10,000uF 50V Electrolytic Capacitor |
U1,U2 | 2 | 741 Op Amp |
U3 | 1 | ICL8063 Audio Amp Transister Driver thingy |
Q1 | 1 | 2N3055 NPN Power Transistor |
Q2 | 1 | 2N3791 PNP Power Transistor |
Notes
1. I know I skipped R4. That is not a problem :-)
2. Distortion is less than 0.1% up to 100HZ and increases to about 1% at 20kHz.
3. I haven't been able to find anyone who sells a suitable T1. You can always use two 24V 5A units in series. If you are building two amps (for stereo), then I would suggest using an old microwave transformer and rewinding it.
4. Q1 and Q2 will require heatsinks.
5. You may have trouble finding U3 because it is discontinued. Please don't email me about sources...I can't find it either. A possible source was sent in by JBWilliams: