Hi,
I'm looking around for a new amp project and I found this one. While I have a few scratch built amps under my belt, I am still learning when it comes to circuits. What is the purpose of the relays in the B- and C+ arms of the PS? Do I need them?
Thanks
Jonathan
I'm looking around for a new amp project and I found this one. While I have a few scratch built amps under my belt, I am still learning when it comes to circuits. What is the purpose of the relays in the B- and C+ arms of the PS? Do I need them?
Thanks
Jonathan
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Hi!
The relais in the B+ of the output stage will be triggered only when the bias voltage is there. This prevenst the B+ from being present to early in case bias is not settled yet and acts as a safety mechanism in case the bias fails, B+ will also be interrupted and thus avoid over current on the precious 300B.
For my taste the 417 is not a good choice as driver for the 300B since it will not have a lot of headroom. It will work however.
Best regards
Thomas
The relais in the B+ of the output stage will be triggered only when the bias voltage is there. This prevenst the B+ from being present to early in case bias is not settled yet and acts as a safety mechanism in case the bias fails, B+ will also be interrupted and thus avoid over current on the precious 300B.
For my taste the 417 is not a good choice as driver for the 300B since it will not have a lot of headroom. It will work however.
Best regards
Thomas
Hi Johnathan,
no, it is much simpler: just turn on the main switch, the rest comes on automatically. With the mains switch on, both EZ81 start to heat up. Driver B+ and output stage bias come up. Once bias voltage exceeds a certain level, the relais for the outputstage B+ gets triggered
Thomas
no, it is much simpler: just turn on the main switch, the rest comes on automatically. With the mains switch on, both EZ81 start to heat up. Driver B+ and output stage bias come up. Once bias voltage exceeds a certain level, the relais for the outputstage B+ gets triggered
Thomas
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