kellys_eye
- Jun 25, 2010
- 6,514
- Joined
- Jun 25, 2010
- Messages
- 6,514
I enjoy watching Youtube videos by The Tech Guy (he repairs hi-end test equipment) and have always admired his variable AC power supply that he often uses to power up equipment that have PSU problems.
He did a video showing the innards of this variable AC power supply and despite its relative complication (seemed awfully more intricate than it really needed to be imho) it is something I intend to reproduce as a New Year project for my own workshop.
I was fortunate enough to purchase a (very) cheap variable low voltage AC supply unit - an ex-schools laboratory unit that delivered 0-28V AC at up to 10A. It is a simple variac powering a standard AC transformer so lends itself to adaptation to a full-scale 0-280V AC supply by the simple addition of another 28VAC secondary mains transformer wired in reverse!
This gives a nice ISOLATED supply that can vary from (as good as) zero right up to past 240V (the UK mains supply) and at a total power of around 250W - more than sufficient for most electronic equipment that I repair, especially TV's and the like.
Some additions I will be making include an interlock to prevent the high voltage side being switched on unless the variac starts at 0V, metering for Volts, Amps and Watts (Chinese all-in-one module), current trip etc.
The finished version will have:
Variable AC 0-28V @ up to 10A - metered V and I
Variable DC 0-40V @ up to 6A (simple BR and smoothing, so unregulated) - metered V and I
Variable AC 0-280V @ up to 1A - metered V, I and W (cumulative too!)
Various switching arrangements will ensure only one type of output can be used at any one time, thermal detection for transformer overheating and, as already mentioned, full mains isolation!
I don't know how much Tech Guy paid for his unit but mine (so far) has cost £10..... another £15 for the second transformer and (say) £15 for the metering. I have all the sundry parts to finish.
Anyone got a New Year project they want to mention? Note, this is not a 'resolution' - I'm useless at those!
He did a video showing the innards of this variable AC power supply and despite its relative complication (seemed awfully more intricate than it really needed to be imho) it is something I intend to reproduce as a New Year project for my own workshop.
I was fortunate enough to purchase a (very) cheap variable low voltage AC supply unit - an ex-schools laboratory unit that delivered 0-28V AC at up to 10A. It is a simple variac powering a standard AC transformer so lends itself to adaptation to a full-scale 0-280V AC supply by the simple addition of another 28VAC secondary mains transformer wired in reverse!
This gives a nice ISOLATED supply that can vary from (as good as) zero right up to past 240V (the UK mains supply) and at a total power of around 250W - more than sufficient for most electronic equipment that I repair, especially TV's and the like.
Some additions I will be making include an interlock to prevent the high voltage side being switched on unless the variac starts at 0V, metering for Volts, Amps and Watts (Chinese all-in-one module), current trip etc.
The finished version will have:
Variable AC 0-28V @ up to 10A - metered V and I
Variable DC 0-40V @ up to 6A (simple BR and smoothing, so unregulated) - metered V and I
Variable AC 0-280V @ up to 1A - metered V, I and W (cumulative too!)
Various switching arrangements will ensure only one type of output can be used at any one time, thermal detection for transformer overheating and, as already mentioned, full mains isolation!
I don't know how much Tech Guy paid for his unit but mine (so far) has cost £10..... another £15 for the second transformer and (say) £15 for the metering. I have all the sundry parts to finish.
Anyone got a New Year project they want to mention? Note, this is not a 'resolution' - I'm useless at those!