Newbie needs salvage advice

[Pierrelenfestey]

So I looked all over this completely unbelievably huge and awesome resource and couldn't for the life of me find any reference to recycling, repurposing or salvaging PSU's from other old or unused electronic goods. If there is mention of salvaging stuff, it's usually caps. I'm aware of the dangers of using second hand goods, especially when dealing with mains electricity, but is there really no option other than to buy new?

As a for instance, could I use the power supply unit from an old VHS recorder? It has a trafo with a number of secondary windings, what seems to be two rectifiers and negative and positive dc voltages coming out of it in the correct voltage ranges. Admittedly I don't know the current limitations of the PSU, but it's free and as long as I'm treating it with the correct degree of caution, I can limit the danger element.

So what I'm asking is, "has anyone built one of these babies entirely from salvaged parts" (excluding the amp chips themselves, perhaps)?

Thanks in advance, guys

[Geleia]

Sure you can use the power supplies salvaged from other electronics. The problem is that most of the time you won't know which transformer is and how much current it can output.

I would recommend measuring with a multimeter all of it's secondary voltages and redo the rectifying though.

[john blackburn]

Hi Pierrelenfestey.

The bulk of the cost of an amp build isn't the amp itself, it is the heatsink, transformer, case, connectors and the like that takes the budget up.

If you are willing to do some skip ratting you can save yourself good money and stop things going to landfill into the bargain. Be warned though it is addictive and surprisingly illegal in the UK.

The older type of pc heatsinks are useful but can be tricky to mount in the chassis. A heatsink from a dead amp will have some form of mounting screws making it easier to work with.

Make sure your donor is discharged though before you go poking around in anything electrical, capacitors can store a charge for a long time and hurt when they bite.

John

[raindog]

Hi Pierrelenfestey.
Personally I prefer using salvaged parts ( resistors, non-electrolytic caps, cases, heath-sinks etc. ) , in fact my gainclone has a case from an old 386DX Targa PC with a pentium 4 heath-sink for the rectifier bridges and a psu case as shielding for the transformer. In your particular case ( VHS recorder psu ) take Geleia's advice and measure the output voltages , you can probably use the psu for a low power application ( preamp , low power amp etc ) since usually VHS recorders ( if I remember correctly ) had power requirements under 100 watts .

[pacificblue]

The power supply from an old video recorder is likely to have low power. You may be able to use it for a preamplifier, headphone amp or the like.

[Pierrelenfestey]

Thanks, guys. That helps alot.

One thing, tho: What commonly thrown away electronic items will usually have the trafo which has a close enough spec to use in a decent chip amp (or am I asking the obvious question to which the answer is - "an old amp").

Also, why redo the rectifier?

[Geleia]

Redoing the rectifying is just one of my likings. It's not really necessary.

For electronics with a good trafo, look for ones with more power requirements. Old TVs must be a good hit, other decent audio amplifiers, etc.

[Boscoe]

I used an old trafo from an amp caps from another and a rectifier from somethiong i had ages ago to make the PSU i use to test my amps, why not?

[madtecchy]

Originally Posted by Pierrelenfestey

Thanks, guys. That helps alot.

One thing, tho: What commonly thrown away electronic items will usually have the trafo which has a close enough spec to use in a decent chip amp (or am I asking the obvious question to which the answer is - "an old amp").

Also, why redo the rectifier?

Hi fellow salvager

You guessed right in my many years of salvaging the most common source for traffos for amplifiers is old amplifiers. there seems to be a lot of industrial smpsu on the surplus market and lots have 24v out and a good amount of current too. Some good output devices can be had from old public address gear i just found two pair 2sc3281 and 2sa1302 a bunch of 5532 opamps in a junked out pa amp. happy hunting
Regards

[m0cea]

Have a look on here for a list of Radio Rallies across the UK.
They are not as good as they use to be but still a great place for salvage bargins.
Don't forget to look under the tables, the big heavy transformers and heat sink are often in equipment under there.
Events: the year ahead | Radio Society of Great Britain