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Tuesday, August 10, 2010

50 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


This is the schematic of the 50 Watt Amp

Parts


Part

Total Qty.

Description

Substitutions
R11200 Ohm 1/4 W Resistor
R21200K 1/4 W Resistor
R3130K 1/4 W Resistor
R511K 1/4 W Resistor
R615K 1/4 W Resistor
R7,R1021 Meg (5%) 1/2 W Resistor
R8,R920.4 Ohm 5 W Resistor
R11110K Pot
R12,R13251K 1/4 W Resistor
R14147K 1/4 W Resistor
C11100uF 35V Electrolytic Capacitor
C210.011uF Capacitor
C313750pF Capacitor
C4,C621000pF Capacitor
C5,C7,C830.001uF Capacitor
C9150pF Capacitor
C1010.3uF Capacitor
C11,C12210,000uF 50V Electrolytic Capacitor
U1,U22741 Op Amp
U31ICL8063 Audio Amp Transister Driver thingy
Q112N3055 NPN Power Transistor
Q212N3791 PNP Power Transistor
BR11250 V 6 Amp Bridge Rectifier
T1150V Center Tapped 5 Amp Transformer
S11SPST 3 Amp Switch
S21DPDT Switch
F112 Amp Fuse
SPKR118 Ohm 50W Speaker
MISC1Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2


Notes




  1. Distortion is less than 0.1% up to 100HZ and increases to about 1% at 20kHz.
  2. 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. Follow the instructions in the 12V To 120V Inverter, execpt wind 26 turns, twist a loop (center tap) and wind 26 more turns. That should work out to around 50 volts. You may need to add or remove turns depending on your transformer.
  3. Q1 and Q2 will require heatsinks.

3 Watt FM Transmitter

This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isn't so bad, a PLL can be used on this circuit.This is a circuit that I've build a few years ago for a friend, who used it in combination with the BLY88 amplifier to obtain 20 W output power. From the notes that I made at the original schematic, it worked fine with a SWR of 1 : 1.05 (quite normal at my place with my antenna).

Schematic





This is the schematic of the 3W FM Transmitter

































Parts







Part





Total Qty.





Description





Substitutions
R1,R4,R14,R15410K 1/4W Resistor
R2,R3222K 1/4W Resistor
R5,R1323.9K 1/4W Resistor
R6,R112680 Ohm 1/4W Resistor
R71150 Ohm 1/4W Resistor
R8,R122100 Ohm 1/4W Resistor
R9168 Ohm 1/4W Resistor
R1016.8K 1/4W Resistor
C114.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,C11,C127100nF Ceramic Disc Capacitor
C6,C9,C10310nF Ceramic Disc Capacitor
C8,C14260pF Trimmer Capacitor
C13182pF Ceramic Disc Capacitor
C15127pF Ceramic Disc Capacitor
C16122pF Ceramic Disc Capacitor
C17110uF 25V Electrolytic Capacitor
C18133pF Ceramic Disc Capacitor
C19118pF Ceramic Disc Capacitor
C20112pF Ceramic Disc Capacitor
C21,C22,C23,C24440pF Trimmer Capacitor
C2515pF Ceramic Disc Capacitor
L115 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L956-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L831.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L1018 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D11BB405BB102 or equal (most varicaps with C = 2-20 pF [approx.] will do)
Q112N3866
Q2,Q422N2219A
Q31BF115
Q512N3553
U117810 Regulator
MIC1Electret Microphone
MISC1PC Board, Wire For Antenna, Heatsinks





Notes

  1. The circuit has been tested on a normal RF-testing breadboard (with one side copper). Make some connections between the two sides. Build the transmitter in a RF-proof casing, use good connectors and cable, make a shielding between the different stages, and be aware of all the other RF rules of building.
  2. Q1 and Q5 should be cooled with a heat sink. The case-pin of Q4 should be grounded.
  3. C24 is for the frequency adjustment. The other trimmers must be adjusted to maximum output power with minimum SWR and input current.
  4. Local laws in some states, provinces or countries may prohibit the operation of this transmitter. Check with the local authorities.

22 Watt Audio Amplifier

The 22 watt amp is easy to build, and very inexpensive. The circuit can be used as a booster in a car audio system, an amp for satellite speakers in a surround sound or home theater system, or as an amp for computer speakers. The circuit is quite compact and uses only about 60 watts. The circuit is not mine, it came from Popular Electronics.

Schematic


This is the schematic of the 22 Watt Amp

Parts

Part
Total Qty.
Description
Substitutions
R1139K 1/4 Watt Resistor
C1,C2210uf 25V Electrolytic Capacitor
C31100uf 25V Electrolytic Capacitor
C4147uf 25V Electrolytic Capacitor
C510.1uf 25V Ceramic Capacitor
C612200uf 25V Electrolytic Capacitor
U11TDA1554 Two Channel Audio Amp Chip
MISC1Heatsink For U1, Binding Posts (For Output), RCA Jacks (For Input), Wire, Board

Notes


  1. The circuit works best with 4 ohm speakers, but 8 ohm units will do.
  2. The circuit dissipates roughly 28 watts of heat, so a good heatsink is necessary. The chip should run cool enough to touch with the proper heatsink installed.
  3. The circuit operates at 12 Volts at about 5 Amps at full volume. Lower volumes use less current, and therefore produce less heat.
  4. Printed circuit board is preferred, but universal solder or perf board will do. Keep lead length short.


Monday, August 9, 2010

Simple Polarity Tester

This tester can be used to check the polarity of any power source, and is therefore very useful when installing automotive equipment, alarm systems or anything else you can think of. Because this circuit is so simple and cheap, even frying one with an over voltage is not a big deal.

Schematic

Schematic for polarity tester

Parts

Part
Total Qty.
Description
Substitutions
R111K 1/4W Resistor
D11Green LED
D21Red LED
D4, D5, D6, D741N4001 Silicon Diode1N4004, 1N4005, 1N4007
MISC1Board, Wire, Case, Probes

Notes

  1. Email Dudley LeRoux with questions, comments, etc.
  2. To use the circuit, just connect your probes to the source under test. If D1 lights up, the left most probe (on the schematic) is connected to positive. The opposite is true if the left probe is negative. If both LEDs are on, the source being probed is AC.
  3. Be careful when using this tester not to probe a source greater than about 12V.

How to Build Electronic Circuits : How a Light Emitting Diode Works

Simple Parallel (Printer) Port Interface


This is the basic interface I used as part of my Computerized Room project. This is the parallel interface only. The 8 bit input card can be found, along with the rest of the project, at Computerize Your Room/House. This interface, as well as the other two interfaces, came from the book "The Robot Builders Bonanza", by Gordan McComb. This interface is also useful for controlling small robots, etc. It is cheap and fairly easy to build, although you should not attempt this project unless you have prior experience with electronics. You probably won't damage anything if you hook it up wrong, but there is always a chance (some parallel ports are better protected then others). If possible, test the project on someone else's, or a school computer :-)

Schematic


This is the schematic of the parallel port interface

Parallel Port Pin Assignments


Parallel port pin assignments graphic

Parts


Part

Total Qty.

Description

Substitutions
U1, U2, U3374LS367 Buffer IC74367, 74HC367
MISC1Case, Wire, Sockests, 18 Pin Socket (For Output), 25 Pin Connector (For Parallel Port), Ribben Cable


Notes


  1. I built the interface on a piece of universal solder board due to the large number of wires that must cross. It is also much easier to fix mistakes then on a PC board. I also used a 25 pin crimp connector to connect it to the parallel port. 26 conductor ribben cable was used to link the connector to the board.
  2. This interface only offers 5 inputs (on some computers it may be less). For more inputs, see Computerize Your Room/House. If you choose to use the inputs, remember that the voltage level can not exceed 5 volts or fall below ground.
  3. This circuit is TTL and therefor must be powered by no more then 5 volts.
  4. You can download control software from my files section.
  5. For more information on programming the parallel port, see Programming The Parallel Port In QBasic or Programming The Parallel Port In Visual Basic.

TRIAC Light Dimmer

This little circuit can be used to dim lights up to about 350 watts. It uses a simple, standard TRIAC circuit that, in my expirience, generates very little heat. Please note that this circuit cannot be used with fluorescent lights.

Schematic


This is the schematic of the TRIAC Light Dimmer

Parts

Part
Total Qty.
Description
Substitutions
R1150K Pot
R2115K 1/2W Resistor
C1, C220.068 250V Capacitor
L11Lamp To Be Controlled (up to 350 watts)
L21Neon Lamp
TR1140502 TRIAC
MISC1Case, Knob, Heatsink For TR1, Wire, Socket For L1

Notes


  1. This circuit is for 117VAC only. 220 or 240 V will burn up the circuit. L1 can be a maximum of 350 watts.
  2. The circuit must be installed and used in a case.

Strobe Light

Disco anyone? Actually, this strobe serves a much more useful purpose then making it look cool when you dance in the dark. You can use it to view fast moving objects, look for craks in PC boards (hold the strobe on the trace side of the board and look from the component side), and it is a great attention getter in a store window.
DANGER: HIGH VOLTAGE DANGER: HIGH VOLTAGE DANGER: HIGH VOLTAGE DANGER: HIGH VOLTAGE DANGER: HIGH VOLTAGE

Schematic


This is the schematic of the strobe light

Parts

Part
Total Qty.
Description
Substitutions
R1110 Meg, 1/4 Watt Resistor
D1, D221N4003 Silicon Diode1N4007
C1, C2210uF 350V Capacitor
C310.1uF 400 Volt Mylar Capacitor
T114KV Trigger Transformer (see "Notes")
FT1Flash Tube (see "Notes")
L11Neon Bulb


Q11106 SCR
S11115V 1A SPST Switch
MISC1Case, Wire, Line Cord


Notes


    Where To Get Parts).
  1. This ciruits is NOT isolated from ground. Use caution when operating without a case. A case is required for normal operation. Do not touch any part of the circuit with the case open or not installed.
  2. Most any diodes rated at greater then 250 volts at 1 amp can be used instead of the 1N4003's.

Simple Colour Organ

This is a simple, one lamp colour organ. It is far less complicated then the Three Channel Colour Organ. It is simply a lamp controlled by an SCR. It can be built in a few minutes, and combined with other circuits to make some pretty neat effects.

Schematic


This is the schematic of the Simple Colour Organ

Parts

Part
Total Qty.
Description
Substitutions
R11500 Ohm Pot
T11500 Ohm/500 Ohm Matching Transformer1K/1K Matching Transformer
SCR11C106Y SCR106B, Teccor S2003LS1
L1110-100 Watt Lamp
MISC1Case, Board, Socket For L1, Line Cord

Notes


  1. L1 can be any 10-100 Watt lamp.
  2. R1 adjusts sensitivity. The greater the resistance, the less sensitive the colour organ becomes.
  3. Since this project is powered by 120 VAC, it must be installed in a case.
  4. You can also use the Teccor S2003LS1 SCR for SCR1. These give better sensitivity and brightness than the C106Y units

Light/Dark Detector

This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light.

Schematic


Schematic for Light/Dark Detector

Parts

Part
Total Qty.
Description
Substitutions
R11100K Pot
Q112N3904 NPN Transistor2N2222
Q21NPN Phototransistor
RELAY19V Relay
MISC1Board, Wire, 9V Battery Snap (if battery used), Knob For R1


Notes


  1. R1 Adjusts sensitivity