From: Sean Breheny <shb7@cornell.edu>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 28 Apr 2020 12:04:49 -0700
Subject: Re: [EE] Seeking audio relay advice
Thread-Topic: [EE] Seeking audio relay advice
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Bob,

Why are you so convinced that reed switches wouldn't suffer the same
problem? It's still a contact and it depends entirely on the material of
the contacts. The original relay sounds like it had gold-plated contacts
which I think should work with dry switching - at least until the gold
wears off. Mercury-wetted is probably the best solution. Another would
probably be to introduce a DC bias current (although I know you don't want
to alter the design of the amp).

Sean


On Tue, Apr 28, 2020 at 2:26 PM Bob Blick <bobblick@outlook.com> wrote:

> Thanks everyone who replied and for the suggestions. I decided to take th=
e
> chance and for $26 I have 20 HB2E-DC24V relays coming from an Aliexpress
> vendor. Although I'm sure what will show up will be relays, whether they
> are counterfeit or used is unknown at this time. The picture and
> description seem correct.
>
> As to the question about the failure mode, it's a contact issue, and the
> symptoms are distortion, noise, and signal dropping out. Cycling the tape
> monitor and input selectors clears it up for an annoyingly short time. Wh=
en
> I originally got the unit I popped the tops off the relays(this unit has
> the original Omron unsealed relays) and squirted Cramolin, that worked fo=
r
> a month or so.
>
> This is a preamplifier, so the signals are all low level audio under 2
> volts AC, and very low current. So it's the textbook low current dry
> contact problem.
>
> I love the idea of hacking the relays apart and putting reed switches int=
o
> the the original magnetic structure. Maybe I'd try it if I didn't have to
> do it for 13 relays, each requiring two SPDT reed switches!
>
> In 2 months when the relays finally arrive from China I'll post a reply
> with what showed up and if they work.
>
> Cheerful regards, Bob
>
> ________________________________________
> From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of John
> Ferrell
> Sent: Saturday, April 25, 2020 10:39 PM
> To: piclist@mit.edu
> Subject: Re: [EE] Seeking audio relay advice
>
>
> On 4/25/2020 5:54 AM, Forrest Christian (List Account) wrote:
> > the real question is what is the
> > failure mode on the relays.
>
>
>
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