TL494- Power supply for VFD

Typically in self made small hardware (DIY), power from mains transformed and rectified using simple wall “cube”. But this cube produces typically 12V. A bit too low for VFD. If I would like to use some higher voltage cube for 25V it will be hard to find, and to much power will be dissipated in 5V supply for logic parts. There is one chip in AT/ATX power supply: TL494 (or analog), pulse width modulator, generator, etc. etc. Switching power supply controller. Using this chip you can build any switching supply, or PWM regulator. Using typical parts from AT power supply and powerful mosfet from mainboard I constructed boosting regulator. Schematics are here.

Press on image of here to see the schematics.

The main parts are: T1, Q1, L1, D1. T1 is used to drive powerful mosfet. Mosfet is connected in simplified way, so called passive on. It must be driven using totem pole schematics, but who cares if it works. L1 is some inductor from old HP printer (about 50 turns, 1cm height, 0.5 cm width with windings, open inductor). D1 is fast schotky diode from some other device. It is SMD part from Motorola- the device is unknown. (Motorola just loves to encrypt devices…some top secret paranoia). The TL494 is connected in alternative way. It can be connected in typical way described in older posts.

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4 Responses to TL494- Power supply for VFD

  1. Mido says:

    Hello ^_^
    what is the value of C6 and C8 ?
    I made the circuit by Multisim but it doesn’t work :( !!!!!
    could you help me please ?

  2. C8 – small value capacitor to prevent switching noise entering error amplifier, 0.01uF or less is ok. If good PCB and component placement, no need for this cap. Bigger values will slow down setting of desired voltage.

    C6 – even smaller cap, it is used to filter high frequency noise. from zero to several hundred of picofarads.

  3. Mido says:

    Thank you ^_^

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