100 transistor circuits

Posted on Feb 5, 2014

A simple way to produce your own speaker transformer by winding turns on a piece of ferrite rod. The primary winding is made by winding 300 turns of 0. 01mm wire (this is very fine wire) over the secondary and ending with a loop of wire we call the centre tap. This circuit is a very sensitive 3-transistor amplifier using a speaker transformer. This can be wound

100 transistor circuits
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on a short length of ferrite rod as show above or 150 turns on a 10mH choke. The biasing of the middle transistor is set for 3v supply. The second and third transistors are not turned on during idle conditions and the quiescent current is just 5mA. This the second simplest circuit in the world. A second transistor has been added in place of your fingers. This transistor has a gain of about 200 and when you touch the points shown on the diagram, the LED will illuminate with the slightest touch. The transistor has amplified the current (through your fingers) about 200 times. This circuit is so sensitive it will detect "mains hum. " Simply move it across any wall and it will detect where the mains cable is located. It has a gain of about 200 x 200 x 200 = 6, 000, 000 and will also detect static electricity and the presence of your hand without any direct contact. You will be amazed what it detects! There is static electricity EVERYWHERE! The input of this circuit is classified as very high impedance. This circuit can be

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