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Programmable Unijunction Transistor (PUT) Circuits
Last Updated on:
Saturday, April 26, 2008 07:31 AM |
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| Links to electronic circuits, schematics, or
diagrams for engineers, hobbyists, students & inventors: |
| Poor man's Frequency Convertor for a squirrel Motor: The idea is opposite
of typical motor frequency convertor where the main voltage is first rectified and later chopped to a variable frequency. Outputting voltage
must be in proportion of frequency. The lower the frequency the lower the voltage must be. This simple circuit is operating as a
cycloconverter. It picks every 3th half wave of the inputting main voltage. The result is 1/3th from the frequency and even from
the voltage. It is near ideal and comparable to the normal motor frequency convertor. Only limitation is the speed control. This is not
stepless but usable speeds are 1/3th, 1/5th, 1/7th and so on from the mains freq. This circuit is dimensioned to the 1/3 frequency division.
Increasing time constant of R2C1 it can operate in more lower speeds. (Electronic circuit design added 02/05) |
| Relaxation Oscillators: A relaxation oscillator is a circuit that
repeatedly alternates between two states at with a period that depends on the charging of a capacitor. The capacitor voltage may change
exponentially when charged or discharged through a resistor from a constant voltage, or linearly when charged or discharged through a constant
current source. With exponential charging, the timing is expressed in terms of time constants RC. In a basic circuit, ...(Electronic circuit
design added 02/05) |
| Silicon Controlled Rectifier Model Railroad Throttles and London Model Railroad
Group SCR Throttle: The following is a schematic drawing of a Silicon Controlled Rectifier type throttle for use on larger scale
model railroads. Three versions of this throttle are shown on this page. They are not sophisticated designs but work well and are tough and
reliable. (Electronic circuit design added 02/05) |
| Unijunction Transistor: The unijunction transistor(UJT)
is a three terminal device with characteristics very different from the conventional 2 junction, bipolar transistor. It is a pulse generator
with the trigger or control signal applied at the emitter . This trigger voltage is a fraction (n) of interbase voltage, Vbb.The UJT circuit
symbol, junction schematic, and characteristic curve are ... (Electronic circuit design added 02/05) |
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