What to do if you have broken the power supply from the computer, but there is no power control for soldering? But such a device will not only keep the soldering iron tip, but also your nerves:)
As output keys in a computer PSU are often used MOSFET — field effect transistor with high output and low current control. I had installed STW9NK90Z together with the desired radiator. Taking it and connecting to a simple scheme of PWM (pulse width modulator impulsy), I got pretty decent power regulator. I needed it for soldering, but this is well suited to incandescent lamps of up to 150 Watts. The maximum load may be greater and depends on the nameplate capacity of the key; the range of power adjustment — from 0 to 100%.
The scheme was simple and very reliable. A master oscillator PWM is assembled on shirokolistvennyh transistors KT315 (and any other silicon n-p-n). Its duty cycle adjust variable resistor R3, and the upper and lower limits — the trimmers R1 and R2. PWM output is connected directly to the key VT3, which, in turn, closes the diode bridge. Load — a light bulb or a soldering iron, at the instant the circuit is connected to 220V. Depending on the duty cycle of the PWM changing the brightness of the filament of the light bulb or the temperature of the soldering iron. The power scheme gives the chain VD2, R8, VD1, C3.
The whole scheme fits in standard electrical gorbochku (see image), and settings — you only need to adjust the resistors R1 and R2 are the lower and upper limits of power adjustment.
A diode bridge you can apply any, with minimum voltage and current is, respectively, 400 volts and 2 amperes. Such bridges exist in a computer PSU, but since they often fly out, be sure to check it before installing. Zener diode VD1 — any stabilizatsii with a voltage of 12 volts. Note on the resistor R8 — its minimum capacity should be 2 Watt.
As a key, you can use any n-channel MOSFET with minimum reverse voltage of 400 volts and a power defined by the required power load. If the load should be measured in kilowatts, then the key can be replaced by a thyristor, for example, КУ202; you will need to pick up an R7 in the range 2-5 ohms.
Vyacheslav Gorchilin, 2014
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