Showing posts with label transistor. Show all posts
Showing posts with label transistor. Show all posts
Tuesday, November 11, 2014
LED flasher with Transistor circuits Diagram
These circuits only flash one or two LEDs. This is opposed to the light chaser circuits that can flash four or more. Of course, the simplest LED flasher is simply to use a flashing LED. The problem with that approach is you have no control over the flash rate, but it does have its use for eye catching displays for selling stuff. The circuits below give you that control, plus they can flash two LEDs alternately.
There are many possible applications for the circuits below, especially for kids, who love flashing lights. Heres some possible uses.
- Railroad crossing signal for model railroads.
- Safety blinkers for bicycles, etc.
- Fun stuff for Halloween, like making those plastic Jack-O-lanterns blink (try using ultraviolet LEDs here).
- Christmas decorations.
- Blinkers to locate items in the dark.
Transistor LED flasher
This circuit has a lot going for it. For one thing, it only consists of two transistors, two capacitors and four resistors. That also means it consumes very little power. You can control the flash rate by changing the size of the 100k resistors (100k makes for a pretty slow rate). You can also control the duty cycle by using resistors of different values on the two sides. The 470 ohm resistors control the current through the LEDs. Normally you want to limit this to 20mA, but to conserve battery power, you may need to limit it even further. You can also connect several LEDs in series, instead of using only one for each side. With red LEDs (1 per side) and the values shown, the circuit draws about 11mA. Heres what the actual circuit looks like:
On this circuit, the green wires connect to the LEDs, but you can mount them on the actual circuit board for some applications. The picture is about twice actual size.
Sunday, September 7, 2014
Small transistor amplifier Ideals
Currently, ICs has been used in many audio amplifiers,especially small circuit. It is convenient to use transistors.But when you need to use transistors, it has several advantages, such as saving you can take old equipment come to made small circuits easier than the IC. Which may be difficult to find. Take a look at these circuits. Maybe you get the idea of it.
Low impedance mini amplifier
This circuit can apply to signal sound source that has low impedance , such as from 4-16 ohm size loudspeakers or telephone earphone that use to replace , Micro phone. If use a loudspeaker replaces the rapidity will enough in sound checking that has been born from walking. The output this can feed reach input of high power amplifier the other next.
Power Amplifier OTL by AC176+AC126
Mr Somsak is my friend who like to make power amplifier so much. but he do not well electronic man. I so introduce he need make easy project before. This circuit is simple power amplifier OTL that mini watt output but is older circuit.
They uses transistors example number are AC176 , AC126 and BC109. which there has other a few components. They are used power Supply Voltage 9Volt only. I hope it will be once circuit so you like and well ideas.
Power Amplifier OTL Cassette Radio Booster by TIP41+TIP42
This is mini Power Amplifier OTL for Cassette Radio Booster. it have transistor TIP41 + circuits of TIP42 Drive speaker sound. Volt supply see in image.
Simple Amplifier by Transistor AC128
I find this in my old circuit electronics book. It is very a small power amplifier, but good quality audio class AB amplifier in hi-fi applications. The component capable of delivering 2W continuously an used the AC128 thansistor into a 8 ohm load and 5W peak. with the proper 9 volt unregulated power supply.
This circuit can apply to signal sound source that has low impedance , such as from 4-16 ohm size loudspeakers or telephone earphone that use to replace , Micro phone. If use a loudspeaker replaces the rapidity will enough in sound checking that has been born from walking. The output this can feed reach input of high power amplifier the other next.
Power Amplifier OTL by AC176+AC126
Mr Somsak is my friend who like to make power amplifier so much. but he do not well electronic man. I so introduce he need make easy project before. This circuit is simple power amplifier OTL that mini watt output but is older circuit.
They uses transistors example number are AC176 , AC126 and BC109. which there has other a few components. They are used power Supply Voltage 9Volt only. I hope it will be once circuit so you like and well ideas.
Power Amplifier OTL Cassette Radio Booster by TIP41+TIP42
This is mini Power Amplifier OTL for Cassette Radio Booster. it have transistor TIP41 + circuits of TIP42 Drive speaker sound. Volt supply see in image.
Simple Amplifier by Transistor AC128
I find this in my old circuit electronics book. It is very a small power amplifier, but good quality audio class AB amplifier in hi-fi applications. The component capable of delivering 2W continuously an used the AC128 thansistor into a 8 ohm load and 5W peak. with the proper 9 volt unregulated power supply.
Original article sourse eleccircuit.com.
Friday, August 22, 2014
Simple 4 Transistor Amplifier for Small Speakers
The schema above shows a 4-transistor utility amplifier suitable for a variety of projects including receivers, intercoms, microphones, telephone pick-up coils, and general audio monitoring. The amplifier has a power isolation schema and bandwidth limiting to reduce oscillations and "motorboating". The values are not particularly critical and modest deviations from the indicated values will not significantly degrade the performance.
Three cell battery packs giving about 4.5 volts are recommended for most transformerless audio amplifiers driving small 8 ohm speakers. The battery life will be considerably longer than a 9 volt rectangular battery and the cell resistance will remain lower over the life of the battery resulting in less distortion and stability problems.
Three cell battery packs giving about 4.5 volts are recommended for most transformerless audio amplifiers driving small 8 ohm speakers. The battery life will be considerably longer than a 9 volt rectangular battery and the cell resistance will remain lower over the life of the battery resulting in less distortion and stability problems.
4 Transistor Amplifier for Small Speakers Circuit Diagram
The amplifier may be modified to work with a 9 volt battery if desired by moving the output transistors bias point. Lowering the 33k resistor connected from the second transistors base to ground to about 10k will move the voltage on the output electrolytic capacitor to about 1/2 the supply voltage.
This bias change gives more signal swing before clipping occurs and this change is not necessary if the volume is adequate. As before, the two 4.7 ohm resistors may be replaced with a single 10 ohm resistor in series with either emitter.
This bias change gives more signal swing before clipping occurs and this change is not necessary if the volume is adequate. As before, the two 4.7 ohm resistors may be replaced with a single 10 ohm resistor in series with either emitter.
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