[JMS] Lambda 28

[dbuska at wi.rr.com]

Hi Ronnie,

That article was recently modified to correct errors in the 
schematics.  You are correct the didoe bridge and electrolytic caps are 
drawn wrong for a negative supply.  The new version appears on Bob 
Sullivans mirror site.  If you copy does not show a revision update on 
the first page and on the schematic page it is the older version.

I'm glad you noticed the error before starting the modifications.  Bob 
also mentioned that a better comparator type op amp might be a better 
choice than my 741.  I forget off had what he recommended, something 
like a LM324.

73

Don N9OO

----- Original Message -----
From: "ronnie.hull" <ronnie.hull at glowbugs.com>
Date: Thursday, August 25, 2005 5:34 pm
Subject: [JMS] Lambda 28

> Got my Lambda 28 P/S yesterday and started modifying it today to 
> provide all 
> the low voltages as per Don's mods at his shack.
> 
> Don I have a question. Looking at your schematic, how are you 
> deriving the 
> negative voltages? Shouldn't you have to switch the leads coming 
> off the 
> Bridge? Coming off the positive end of the bridge, to the positive 
> side of 
> the  22mf cap, will give you +68vdc..   unless I'm reading 
> something wrong 
> there.
> 
> anyway, I had to order a 1mh choke and a 5vdc relay and should 
> have them on 
> monday, so I can put the hv sense circuit in then. I have a HP 0-
> 500vdc bench 
> supply I can use to test the hv sensing circuit.
> 
> Anyway, when I get this done, all that will be lacking is the HV 
> Supply and 
> finishing up the modulator front panel
> 
> getting closer y'all !!
> 
> 73's
> 
> Ronnie
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