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the3dman

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I have a discontinued mixer from Europe that I don't have a power supply for, I found a picture of the one I need, but is is not for sale anywhere. So I would like to make one for it. I have made AC/DC ones in the past, but this appears to be AC/AC which I have never seen before, so maybe someone here can help me with how to make this. Here are the specs:

Input: 120v~/60hz/210mA/20W
Output: 2*17.5v~/2*650mA

Any help you can give would be awesome.
Thank you.
 

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audioguru

Well-Known Member
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Many transformers have dual primaries and dual secondaries so that they work from 120VAC or 240VAC. Just find a 120V one that has two 17.5V (or 18V) secondaries at at least 650mA each.
 

audioguru

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The original transformer did not have a current-limiting circuit. The mixer draws only as much current as it needs which might be only 500mA.
 

the3dman

New Member
Thankyou very much! Just for my future knowledge how can you tell that it does not have a current limiting circuit?
 

ericgibbs

Well-Known Member
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Thankyou very much! Just for my future knowledge how can you tell that it does not have a current limiting circuit?
The reason many custom power supplies are 'ac' is because the rectifier diodes are inside the equipment the psu was specifically designed for.

As agu says the mixer will draw as much current as it requires to operate, the 650mA rating, is the maximum the psu will supply.
 

the3dman

New Member
18v with dual secondarys seem to be pretty hard to find do you think I could use a 24v and make a circuit to step the voltage down to 18v?
 

ericgibbs

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Hero999

Banned
What's the supply in your area? If you filled your location in then we would have suggested the right voltage.
 

Hero999

Banned
Sorry, you did say 120V in your original post.

The problem I think you'll have is getting the connector for it so you might have to change the socket on the mixer.

Digikey sell a range of transformers with a twin 18V secondary and will supply the requeired current. You'll need to put the transformer in an enclosure which you can build or buy.

Digi-Key - 185C36-ND (Hammond Manufacturing - 185C36)
Digi-Key - 595-1033-ND (Signal Transformers - 14A-30-36)
Digi-Key - 237-1080-ND (Triad Magnetics - VPP36-820)
Digi-Key - MT3141-ND (Tamura - PL30-36-130B)
 
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