I need help choosing a transformer, the one that I'm looking at is "Toroidal Transformer, 160VA 0-35/0-35 "
Is that 35v 4.5A?

I have a stepdown circuit with input voltage no bigger that 37V, will this transformer exceed 37v

 

Hello,

An 160 VA transformer of dual 35 Volts will have a current rating of about 2.25 A on each 35 Volts output.

Bertus

 

and more amps with lower output? how much heat will it generate?

 

Hello,

No, you can not draw more than 2.25 Ampere on each output.
If you draw more current, you will burn your transformer.

Bertus

 

how easy is it to build a current limiter? (and the heat question?)

oh and won't lower voltages pull less current then

 

It is very easy to modify a toroidal transformer, either by taking turns off, adding turns or simply adding a small secondary if needed.
In the case of the double pair windings, they are usually wound bi-filar which allows removing/reducing both windings at the same time, if needed.
Approx: 2 turns/volt.
Max.

 

You can use LM3xx to build current regulator.It will require heatsinks.
After rectification and capacitors you will have 50V at the output.

 

oh and won't lower voltages pull less current then

Modifiying for lower voltage = higher possible current up to the Va rating.
What voltage are you aiming for?
Max.

 

aiming for 37vols (limits of my stepdown switching power supply that ISB123 helped me with in the wattage in voltage devider thread), thats why I need the transformer after rectification and capacitor not to exceed 37volts
what would this one be? http://www.fort777.co.za/index.php?main_page=product_info&cPath=269_456_676_679&products_id=3774 Toroidal Transformer, 120VA 0-30/0-30
can't you trim the 50V with a resistor to 37V

 

After rectification and smoothing 30v = 42vdc (30ac x 1.414).
As I mentioned it is comparatively easy to modify a toroidal, I have customized many in the past.
For 37vdc a 26vac is required.
Max.

 

Why not just buy a 36 volt power supply?
http://www.mpja.com/36-Volt-Power-Supply/products/543/

 

I'm wary of adjusting a R600 device. Not only does that power supply exceed my budget by about ZAR200, shipping is going to add another ZAR200-300, so no, not an option
the cheaper one is withing my budget, but probably not after shipping

FOUND IT:
http://www.mantech.co.za/ProductInfo.aspx?Item=372M0368

350 WATT SINGLE OUTPUT ENCLOSED SWITCHING POWER SUPPLY
INPUT: 90-132VAC / 180-264VAC OUTPUT: 36VDC @ 9.7A

 

The advantage of a linear supply is it tends to be a alot more rugged and in the event it caves in it can be fixed relatively easily.
This if you do not really need a tight regulated supply.
Max.

 

ok , well other than being a switching supply, it's in my price range, it handles high amperage, it's got built in short/overload prrotection, which I can't build because heatsinks (other than cpu heatsinks) doesn't exist in cape town, so unless the switching part is really a problem, this is the power supply for me. your comments/advice please?

 

You are still going to need to adjust the voltage since its single voltage PSU.

 

but can't I use the switching power supply we built in wattage in resistor devider thread?

 

You can but with 30k pot.

 

If the load varies at all significantly, NO.
No regulation and a power waster.
Max.

 

If the load varies at all significantly, NO.
No regulation and a power waster.
Max.

I don't know yet what my applications will be, but with the lack of heatsinks can you suggest a better solution?

 

Why do you need to drop the voltage if the power supply has the output you need?
Max.