A stereo pre amplifiers with active tone control circuit that has been popular for more than 40 years is this circuit which use the RC4739 as main components. Due to its features that the bass heavy, and treble sound is crystal clear. Due to its features that the bass heavy, and treble sound is crystal clear, still chose this project. Figure 1 the schematic circuit diagram This pre tone include of 2 main sector are: – The first, IC1 act as the pre amplifier circuit for the signal amplifier from the Magnetic pickup or microphone and – The second, IC2 …
Today lets to see the simple FM transmitters,90-100MHz that use two transistors, apply power supply with 1.5V battery The coil-L is 8.5 turns of 22 swg wire wound with a inside diameter air core of about 5mm. Then stretch the coil to width of 9 mm.  Figure 1 The schematic circuit diagram To tap out to the antenna at 3 turns (from input voltage) then adjust the all current of this circuit by Stretching or shrinking the coils and adjustable TC (trimmer) to have the current approximately 3mA the frequency in 90-100 MHz range. Figure 2 the components layout connection …
My son is very interested in the LED. He want to created the simple LED flasher circuit. But we should learn the principles of the LED before. Started to use the LED circuit as Figure 1. Includes Battery, Resistor and LED – Its shape – symbols (When drawing the circuit, if the actual shape it waste so much time, symbols should be used) Things should remember The battery and LED are polarity must be used correctly. Next Step… How much voltage’s LED? I recommend breadboard because it does not require electric soldering iron. Perfect for my son. He experimented to …