[ARC5] 24vdc power

[Mike Feher]

What kind of generalization is this, Brian. More than likely drawn from a sample of one, yourself. 73 – Mike 

 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

848-245-9115

 

From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of Brian Clarke
Sent: Tuesday, September 6, 2022 8:42 AM
To: 'Tom Lee' <tomlee at ee.stanford.edu>; arc5 at mailman.qth.net
Subject: Re: [ARC5] 24vdc power

 

For newly minted silicon diodes, you may well be correct, Tom.

However, radio amateurs usually have deep pockets and short arms and hence, attend ham fests and swap meets to pick up components whose provenance may not aspire to the Guinness book of records.

73 de Brian, VK2GCE

 

From: arc5-bounces at mailman.qth.net <mailto:arc5-bounces at mailman.qth.net>  [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Tom Lee
Sent: Tuesday, 6 September 2022 3:41 PM
To: arc5 at mailman.qth.net <mailto:arc5 at mailman.qth.net> 
Subject: Re: [ARC5] 24vdc power

 

As a crude approximation, the reverse leakage of an ordinary silicon rectifier at room temp will typically be about 9 orders of magnitude below the forward current rating. So, a 100A rectifier can be expected to have a leakage current of perhaps 100nA. You may see larger numbers on datasheets, but those are generally sandbagged so that the manufacturer doesn't have to spend the money on actually testing that parameter.

Now, if you're still using seleniums or copper-oxide rectifiers, I might worry about the reverse leakage...otherwise, battery self-discharge will dominate by large factors.

--Cheers
Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 9/5/2022 22:22, Brian Clarke wrote:

Not a good idea, Bob.

 

Some batteries, particularly lead-acid, see the pulsing DC as charge-discharge cycles, shortening their lives. Diodes do not have infinite reverse resistance; so, leaving a battery connected to a transformer + rectifier combo will discharge the battery a bit faster than shelf life.

If you don’t use a battery or regulator to smooth out the pulses, your outgoing radio signal will be modulated with 100 Hz or 120 Hz noise.

 

73 de Brian, VK2GCE 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20220906/166a8b36/attachment-0001.html>