[AMRadio] Cap Substitution


jeremy-ca km1h at jeremy.mv.com
Fri Feb 15 09:14:34 EST 2008


What is the full AC secondary voltage of the tranny, 6 or 12V? He may have 
been attempting a doubler or tripler circuit and you got it with parts 
missing or miswired. If one diode was across the relay coil it is to prevent 
back EMF.  A 24V relay will usually pull in around 16-18V.

Carl
KM1H


----- Original Message ----- 
From: "Bob Macklin" <macklinbob at msn.com>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Thursday, February 14, 2008 11:05 PM
Subject: Re: [AMRadio] Cap Substitution


> With a single 1N4007 and a capacitor you will have a filtered 1/2wave
> rectifier. It should charge to .9 time the 24V. That should be OK.
>
> You could use 4 1N4007s in a bridge and not use the capacitor.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa,
> "Real Radios Glow in the Dark"
> ----- Original Message -----
> From: "JT Croteau" <jt.n1ese at gmail.com>
> To: "Discussion of AM Radio in the Amateur Service"
> <amradio at mailman.qth.net>
> Sent: Thursday, February 14, 2008 7:55 PM
> Subject: Re: [AMRadio] Cap Substitution
>
>
>> Nope Bob, this guy definitely only had three 1N2069's in parallel -
>> two cathodes to one anode connected directly to a 6.3V tranny.
>>
>> I'm not looking to put it back the way he had it, I'm putting it back
>> the way the schematic shows it with a 1N4007 instead of the 1N91 shown
>> (already have in my junk box) and a filter cap.
>>
>> I'm just trying to understand how he was getting the 24V relay to work
>> with a 6.3V tranny.
>>
>> - JT
>>
>> On Thu, Feb 14, 2008 at 10:49 PM, Bob Macklin <macklinbob at msn.com> wrote:
>> > Connecting diodes in parallel does not really effect the current like
>> >  connecting batteries in parallel. The diode with he lowest forward 
>> > drop
> will
>> >  handle most of the current.
>> >
>> >  But if you really had diodes connected with anode to cathode you don't
> have
>> >  a rectifier. That configuration is used in voltage limiter circuits.
>> >
>> >  Got to Radio Shack and get some 1N4000 series diodes and use them for
>> >  rectifiers. You only need one for a 1/2wave rectifier. Or 4 connected
> in a
>> >  bridge for a full wave rectifier.
>> >
>> >  Are you sure the ones you have are not connected in a bridge circuit.
> There
>> >  would be 4 diodes. And 2 of them would have the cathodes connected
> together.
>> >  The other 2 would have the anodes connected together.
>> >
>> >
>> >  Bob Macklin
>> >  K5MYJ
>> >  Seattle, Wa,
>> >  "Real Radios Glow in the Dark"
>> >
>> > ----- Original Message -----
>> >  From: "JT Croteau" <jt.n1ese at gmail.com>
>> >  To: "Discussion of AM Radio in the Amateur Service"
>> >  <amradio at mailman.qth.net>
>> >
>> > Sent: Thursday, February 14, 2008 7:38 PM
>> >  Subject: Re: [AMRadio] Cap Substitution
>> >
>> >
>> >
>> >
>> > > As a follow up to all this talk..
>> >  >
>> >  > The person who did this mod, was rectifying the power to this 24V
>> >  > relay with three 1N2069's in parallel with 2 cathodes facing one
>> >  > direction and the other cathode facing the opposite direction. 
>> > These
>> >  > were wired to a dedicated 6.3V tranny he also added.  Any idea why 
>> > he
>> >  > would have done this rather than using the 24V tap on the filament
>> >  > transformer specially there for a 24V relay?  I measure roughly 26V
> on
>> >  > this tap so I would assume the tranny is fine.
>> >  >
>> >  > --
>> >  > JT Croteau, N1ESE - Manchester, NH (FN42gx)
>> >  > Contest Manager, TARA Skirmish
>> >
>> >
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>>
>> --
>> JT Croteau, N1ESE - Manchester, NH (FN42gx)
>> Contest Manager, TARA Skirmish
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