Inside Circuits

This is a high quality power supply with a continuously variable stabilized output adjustable between 0 and 30VDC. the LM 723 is the heart of the power supply which drives the BD137 and then the 2N3055. The circuit provides short circuit protection. And has great stability at voltage changes. Drive the circuit with 24 Volts 3A from a transformer. the 2N3055 needs a good heat sink.

That RF Amplifier is for boosting small fm transmiters and bugs. It use two Philips 2N4427 and its power is about 1Watt. At the output you can drive any linear with BGY133 or BLY87 and so on. Its power supply has to give 500mA current at 12 Volts. More voltage can boost the distance but the transistors will be burned much earlier than usual.! In any case do not exceed the 15Volts. The Amp offers 15 dB in the area of 80Mhz to 110 Mhz. L4, L5, and L6 are 5mm diameter air coils, 8 turns, with wire 1mm wire diameter.An easy project, with great results.

A stereo power amp designed for use in portable players and radios. A 3V supply can be used to drive headphones providing 20mW in 32 Ohms per channel, and a 9V supply will provide 1W in 8 Ohm per channel for small loudspeakers.

This circuit uses a stereo amplifier IC in a 14-pin DIL package that requires very few external components to make a complete 2 Watt per channel power amplifier. The LM1877N-9 is suitable for use with 8ohm or 16ohm speakers.

This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter, L2= 1 turn - 10mm diameter. R9 trimmer controls the modulation gain. The tunning is easy by controlling C9 trimmer (88-108 MHz). The RFC J should be the VK220J with ferrite (VK200 is not suitable). You will be amazed how well this little monster can transmit several kilometers excellent quality sound. Feed input from a simple cd player or PC (win amp) or just connect a microphone. Enjoy!

This circuit uses the TDA2040V which is a monolithic power amplifier IC intended for use as a high quality, class AB audio power amplifier. Typically it provides 22W output power into 4ohm with 0.5% distortion, from 32V supply. The device is designed to operate from a split power supply and no electrical isolation is needed between the mounting tab and its heatsink. It provides a high output current and has very low harmonic and crossover distortion.

This Circuit is based on the LM3876. A 11-pin plastic package IC with high performance audio power amplifier, an output mute function which can be used to eliminate switch-on and switch-off "thumps" to the loudspeaker load. It is capable of delivering 40W continuously into 8ohm load, and is fully protected using established techniques. The output stage is protected against short circuit to ground or either supply rail. Protection against transients from inductive loads is also provided at the output stage via internal clamp diodes.

This very high quality audio amp is based on the TDA1514A, a 9-pin flat package IC. The heatsink must be insulated from ground. The amplifier will deliver 40 watt into an 8ohm load with a 27.5 volt power rail or 40 watt into 4ohm load with a 21 volt power rail. The IC is designed to meet the requirements of digital sound sources such compact disk players etc. The total harmonic distortion at 32watt is less than 0.0032%. An output mute circuit prevents switch-on and switch-off clicks, and is totally protected against short-circuits and thermal runaway. The metal plate on the package is connected to pin 4.

That Circuit is a UHF TV linear amplifier for small TV transmitters with output aroun 100-200mW. The transistor BGQ136 comes with SOT-122 case has gain of 13dB at 800MHz. So with input 100mW you get 2W output and for 200mW you get 4W.

This small circuit is a Linear amplifier for driving small UHF TV transmitters. Its gain is 7dB and can amplify a signal between 450-800 MHz. You can drive the circuit with 1 to 1,5 Watts signal. Better use double layer PCB with the second layer connected to earth. Use a stabilized power supply 25 volts and at least 5Amps.