19 May
2009
19 May
'09
6:36 a.m.
Dwight,
I think a little explanation is in order, otherwise your info borders on
incorrect. You need to increase the CURRENT rating of the transformer by
1.4, but this only applies to a full wave rectifier topology and not a full
wave BRIDGE topology.
reference: The holy book " The art of electronics " page 47
Best regards, Steven
Hi
I forgot to mention. You need to derate the transformer
as well. The problem is that the current flows when the
voltage is the highest ( or close to it ). The math is a little
complicated but it means you need to increase the rating of
the transformer by at least 1.414.
If you can't find a transformer with the right windings,
I recommend looking at toroidal transformers. These can
easily have turns added to increase or buck the voltage
of the secondary.
Dwight
----------------------------------------
> From: lynchaj at yahoo.com
> To: cctalk at classiccmp.org
> Subject: S-100 power supply transformer
> Date: Sun, 17 May 2009 16:51:44 -0400
>
> Hi! Does anyone know of an available transformer suitable for making an
> S-100 power supply? I need 120VAC input and 10VAC output and +/- 18VAC
> outputs.
>
> The best I solution I can find is two separate 80VA transformers; one
> parallel 10VAC output and another 36VCT output which can be configured
for
+/-18VAC
outputs.
---snip---
Hi
What you want is an 8 volt and a 13.5 volt AC. You forget
that the DC voltage is created from the peaks not the RMS
average. You have to account for diode drop as well.
That is how I got the numbers. I assumed full wave rectification
and .6v per diode.
Dwight