True bypass relays + 12v PSU for Dual mono and Stereo project

[marcfrom]

Yes, go ahead.

But connect only one secondary 0V and 25V.

Anyway check the voltage just after the Diode Bridge with the bypass mode on to protect the relays, it must be less than 35V,
I think you'll find just a bit more than 25 V DC

 

[dandeurloo]

Just tested it.  Good to go. 

Thanks!

 

[dandeurloo]

Anyone have any idea on what would be a good option for powering the bypass boards in an la2a?  The transformer has 2 x 120,110 V Primary. 250-0-250 at 40 mA. 6.3V CT at 2 A.

Any help would be great.  Thanks

 

[marcfrom]

Have you the datasheet of the transformer ?

 

[marcfrom]

If the transformer have a 6V output the solution is:

Replace the 12V relays with this 5V relays:

http://www.newark.com/te-connectivity-potter-brumfield/rt424005f/power-relay-dpdt-5vdc-8a-pc-board/dp/17C6452?Ntt=RT424005F

And replace the L7812CV with a L7805CV.

 

[dandeurloo]

Cool. Good idea. 

I think these relays at digikey should work as well.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=Z3090-ND

Here is the regulator from digi.

http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=L7805CV&x=0&y=0

 

[marcfrom]

The regulator is ok
for the relays the values are ok, but Check the dimensions And pinning to be sure.

 

[dandeurloo]

Do you guys think I will fire my 7812 by trying to regulate 30v's down to 12 by heat?  I had someone suggest I put in a separate PSU for the relay's in my stereo 1176.  I figured I would ask here to see what you guys think?

I am using the suggested Heatsink for this PSU.

Thanks

 

[marcfrom]

As i told you, look the second page of L7812CV datasheet.

http://www.datasheetcatalog.com/datasheets_pdf/L/7/8/1/L7812CV.shtml

L7800 series from 5V to 18V can accept 35V maximum input.

This reg can accept  35 DC voltage maximum input, so 30V is ok. The reg just will be a little hot.

I suggest to go with this, if not you can connect a 12V transformer to your bypass board, but i think it's not necessary.

 

[eparg]

Are PCB's still available? The link to buy them in the OP is dead.

Thanks!

 

[marcfrom]

Yes, the Bypass Board still available.
PM me.

Marc

 

[Nedrum]

I'm testing one of these strapped in dual mode configuration using the Potter and Brumfield RT424012F relays. After I close RBypass or LBypass, the relays briefly switch but don't stay switched. (Power looks ok; I get 12.24 volts.)

Anyone have a similar issue?

 

[marcfrom]

Strange, can you post a pics?

 

[Jitter]

Somebody can shows the wiring from pcb to switch for a stereo mode work?

Thanks.