Bridge rectifier output voltages for 6.3v relay power supply

[Randy Lahey]

Forgive me if this has been asked many times in the past - I did a quick search but couldn't find a solution.

I am installing Hoffman's relay switching circuit in an amp and I am only measuring +3vdc and -3vdc on either output of the bridge rectifier which is fed 6.3vAC from a dedicated 6.3v transformer.

I understand I should see 9vdc at the output - why the low voltage? It's obviously not enough to actuate the relay.  I have measured and confirmed the correct orientation for all components on the relay switching power supply board.

I should also mention that the 6.3vac filament supply has a virtual centre tap with 150R resistors.  I have also not grounded the relay power supply board.

Any suggestions?
Thanks!

[SEL49]

The output is taken BETWEEN the negative and positive terminals of the bridge so that would give you about 6V pulsed DCV. Add a filter cap between the negative and positive terminals to increase the voltage to about 9VDC.

[Willabe]

Lots of relay information in this thread, Relay circuit & layout board & ft. switch;

https://el34world.com/Forum/index.php?topic=14348.0

It's found in Archives of favorite topics, 2nd in the list;

https://el34world.com/Forum/index.php?board=11.0

[SEL49]

I should also mention that the 6.3vac filament supply has a virtual centre tap with 150R resistors.  I have also not grounded the relay power supply board.

Since this is a dedicated transformer that is not being used for tube heaters, you don't need a center tap. So remove the 150Ω resistors and just connect the bridge negative terminal to chassis ground.

[acheld]

I highly recommend Doug's little relay power supply board.  Small, inexpensive, works great. 

Voltage also depends on the voltage regulator you're using, right?

https://hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=Lamps&ORDER_ID=559940839#google_vignette

[rake]

I highly recommend Doug's little relay power supply board.  Small, inexpensive, works great. 

Voltage also depends on the voltage regulator you're using, right?

https://hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=Lamps&ORDER_ID=559940839#google_vignette

+1! It's also neat, clean & all the bugs have been worked out of it already. Simply feed it the heater supply and it's ready to go!

[Merlin]

This guy asked exactly the same question four years ago. May be helpful to you:
https://ampgarage.com/forum/viewtopic.php?t=33226