Transformer for 1176 50 VA too much ??

first hi to all at the new forum ! :grin: :grin: (after the recording.org prob. :twisted: :evil: )


do you think 50 VA torroid 2*24v is to much for the gyraf 1176 ??

I ordered 30 VA but I got a message that they are not availlaible for the next two month at my source (allready payed ...-

is it better to wait for the 30 VA version or can I take the 50 VA instead ??
both have the same price ? can there be problems due to a too big trafo (its 1A instead of 500ma) ?? more magnetic interference or hum ?

a short statement from "Jakob" would be great whats the wright wattage of the transformer (or between which values it should be for best results and possibly no hum or interference)


please let me know your opinnion..

Nik

I'm no expert, but I think you should be fine as long as the mechanical size of the transformer is the same. The 1176 will draw a set amount of current, having a larger VA transformer won't hurt the circuit as long as you use a proper fuse. As far as magnetic interference, I don't think you should encounter any problems because you are still drawing the same current as you would with a smaller VA transformer...

Am I right????

Ian

...

thanks so far for the answers, has anybody tried a 1176 with 50 VA torroid ?


Nik

50VA toroids should work fine. You'll have lots of power for meter illumination :razz:

I actually think I have a 50VA toroid in one of the protos.. We use 2x24/50VA for our headphone driver boxes as well..

On the other hand, if you use standard EL-core in stead of toroid power transformers, you could run into trouble, as those has higher stray magnetic field with larger size cores.

Jakob E.

hi, are we talking about the stereo (2 X mono boards) version or the mono version (1 board)

hi,
here's what mnats had to say about his dual mono G1176 build:

Found they were only drawing about 37.4mA each from the positive rail (no lights) so I put a smaller 30VA transformer in there to power both sides instead of the 50VA I had in there before.

Click to expand...

so basically, if not using a lot of extra current draw due to meter lighting and such a 30VA PS transformer should work fine since each board is only drawing around 37.4mA. That said, you should make sure that the PS transformer you get also has a high enough current rating for the total unit.
cheers,
grant

will those hammond toroidals stocked at mouser do the trick? i assume i need 120v primary and 24 v secondary (series at 0.63?). not sure about the VA .. would 15 be too low?
thanks

try the y23 series from avel lindberg

http://www.avellindberg.com

ed

well since the orginal thread was how much is tooo much, my question is how low can i go with the VA rating? is 15 too low? do i need dual secondaries? i can't find this in the meta on 1176.

thanks,

I recently spent allot of time thinking about this and looking into the specifics of what I'm doing and how it's supposed to work. (easy to do when you don't have all the cash at once to buy all the parts)

Anyways I found this link that helped me.

http://www.mcitransformer.com/i_notes.html

The 1176 power supply looks like a Dual Complementary Rectifier with offset +30/-10 voltage and there is a formula there for what size of transformer you really need.

Reference example 3 you see a +/- 15V 50 ma power supply circuit and the calculations specify use of a 3.5 VA 36V Center Tap transformer. Again this is just a reference to example #3 not specifics for the 1176.

There is also a formula to look at how much power is dicipated from the regulator at full line load.

I may be wrong but at least I'm trying..