Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Transformer wiring

Status
Not open for further replies.

frogmasked

New Member
Hi guys.
I have recently purchased a brand new 36VCT, 1.5A transformer from
jameco for use in a 15v bipolar power supply (https://www.nutsvolts.com/media-files/11/January%201998%20Thomas%20Henry%20-%20Power%20Supplies%20for%20Electronic%20Music.pdf)
I haven't worked with AC before and I Don't know how to wire this thing up.
The picture in the article doesn't look quite the same as the schematic.
I have included some pictures of the transformer.
If anybody could give me some tips on wiring this thing up
or just some educational links on AC that would be great.

thanks.
 

Attachments

  • Photo 83.jpg
    Photo 83.jpg
    84.3 KB · Views: 242
  • Photo 84.jpg
    Photo 84.jpg
    85.6 KB · Views: 230
It's difficult to tell without having a datasheet but I assume that the side with three tags is the secondary and the side with four tags is the primary. There are probably two 120V primaries which need to be connected in series if it's being used on a 240V supply and in parallel if it's being used on a 120V supply.

Be careful the mains voltage can kill and even 36VAC can give you a small shock.

C2 and C3 are also a little small, according to my calculations they should be at least 1300:mu:F so use 1500:mu:F which is the nearest standard value up.

How much current do you want to draw continuously?

A 1.5A transformer is fine for up to 1A of output current, for 1.5A you need a 2A transformer.
 
Check the resistance of the windings. The primary will have a lot more resistance than the secondary.

If, as Hero999 says, the primary consists of two 120 V windings, you have to make sure that connect them up the same way round.

Check the resistance between the 4 terminals. I would expect the similar resistances between 1 and 2 as between 3 and 4. They may be about 20% different, but the difference between that and the secondary will be a lot more.

It would be normal to connect Line to 1 and Neutral to 4 for any supply voltage.

If the mains is 230 V, connect 2 to 3 as well

If the mains is 120 V, connect 1 to 3 and 2 to 4 as well.

However, a data sheet always helps.
 
It's difficult to tell without having a datasheet but I assume that the side with three tags is the secondary and the side with four tags is the primary. There are probably two 120V primaries which need to be connected in series if it's being used on a 240V supply and in parallel if it's being used on a 120V supply.

I go along with that basically. To me it seems there are eight tags on one side, four on top and four at the buttom.

It would be advisable to obtain a data sheet.

Hans
 
Last edited:
I guess you could figure it out with an ohmmeter/voltmeter and a 16v or 24v doorbell transformer (use it to inject voltages and read the V on the other windings). Under no load they'll read 20% high but you can approximate the turns ratios this way.

We kinda' know what we're looking for, and with these pins taken two at a time or three at a time, how bad can it be?
:p
You can also use the doorbell thing to check winding phasing.

Permutations and combinations!
 
Last edited:
Thanks for all the replys guys.
So the side with 4 is primary and 3 is secondary?
And I would connect line to pin 1 and 3 and neutral to 2 and 4?
And I suppose on the other side there would be the 2 outs and a ground?
And if I was wiring a switch and a fuse in there where would those go?

Thanks again.

EDIT: and hero999 I think it's supposed to draw .75A you can get all that info from the link
I posted.
 
Last edited:
You aven't filled in your location or stated your mains voltage so we don't know whether you're right or wrong.

A good way of testing the transformer is to put a 100W incandescent light bulb in series with it and put it on the live side, not the nuetral.
 
The Jameco transformer part number 104417 looks exactly
like the transformer you have pictured there, and since
you ordered it recently it is probably just that.
They dont list a data sheet however, so the following
tests will help you determine how to wire the transformer.


In your picture showing the 4 terminals, the
most likely winding orientation is
S1 F1 S2 F2
where
S1=start winding 1
F1=finish winding 1
S2=start winding 2
F2=finish winding 2

To make sure of this, short out F1 to S2, then
connect a small ac voltage from another transformer
output to terminals S1 and F1, then measure the
voltage across S1 and F1 and record this, then
measure between S1 and F2 and record this.
If the above orientation is correct, the voltage
measured across S1 and F2 will be TWICE the voltage
across S1 and F1 (or nearly so). If this difference
voltage is ZERO volts, then flip S2 and F2.

Once you determine S1, F1, S2, and F2, you can then
wire like this:

For 230vac input, connect F1 to S2, apply 230vac
across S1 and F2.

For 120vac input, connect S1 to S2 and F1 to F2,
then connect 120vac between S1 and F1.

I strongly also advise to use a fuse rated for 1 amp
between the supply (230vac or 120vac) while trying
this out, just in case something gets hooked up
wrong. Without this fuse the transformer could
be damaged permanently and possibly one of the
windings could blow off of the core, which could
spew very hot molten copper in all directions.
Of course safety goggles are also a must.
 
a fuse rated for 1 amp

A 120w bulb?
This assumes that the 10 to 15A that the bulb draws for a few dozen mS does not exceed the (I^2)T rating of the transformer windings.
 
Last edited:
Wow, thanks for all the replies.
This has been a huge help.
Anyway I live in the US so I'm assuming it's 120v.
And I was planning to put a fuse in there also.

thanks again.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top