Trying to learn something, against my better judgment

[athos56]

After plowing through a few threads in an effort to educate myself, I came across this, and I need a little help. I get most of it, it sends a constant voltage to the filaments, but what does the Resistor/LED bit at the end do. I tried reading the data sheet but couldn't figure it out. Thanks

[AKN]

Hi,

"Power on" indicator.

[athos56]

Hehe, really?, if that was it I'd feel kinda dumb...wouldn't be the first time

[AKN]

Well we could narrow it to a "glow on" indicator, I cannot see any other purpose. The impedance in the circuit is very low so the led current will not have any influence.

[Miles Prower]

Originally posted by athos56
After plowing through a few threads in an effort to educate myself, I came across this, and I need a little help. I get most of it, it sends a constant voltage to the filaments, but what does the Resistor/LED bit at the end do. I tried reading the data sheet but couldn't figure it out. Thanks

It's a "Heaters On" panel light. It's always a good idea to include that indicator when you separate the HV and heater supplies, especially where the HV is provided by a SS power supply that otherwise doesn't indicate power up. That way, you can avoid cathode stripping by hitting cold VTs with the full HV, or "sleeping sickness" by running hot cathodes without HV.

[athos56]

Thanks for the responses! Next time I'll try and find a harder question to become confused about

[ErikdeBest]

It's a "Heaters On" panel light. It's always a good idea to include that indicator when you separate the HV and heater supplies, especially where the HV is provided by a SS power supply that otherwise doesn't indicate power up. That way, you can avoid cathode stripping by hitting cold VTs with the full HV, or "sleeping sickness" by running hot cathodes without HV.

I suppose that with separated you mean two different trafo's? Wouldn't it be better than to connect a relay to the primary of the HV trafo, and activate this (solid state) relay from a (rectified and regulated, maybe delayed) voltage of the heaters? Surplus relays aren't that expensive.

Erik

[beamnet]

I think he refers to a standby switch. It is a switch that cutts off the HV at the secondary side to be able to glow the tubes first before applying HV.

Somestimes the switch is bybassed by a resisitor to help the emission starting softly.

Any tube amp without slow rectifier tubes should have such a switch, either manual or automated through a relay.

[Miles Prower]

Originally posted by beamnet
I think he refers to a standby switch. It is a switch that cutts off the HV at the secondary side to be able to glow the tubes first before applying HV.

Somestimes the switch is bybassed by a resisitor to help the emission starting softly.

Any tube amp without slow rectifier tubes should have such a switch, either manual or automated through a relay.

Perzakly

[athos56]

I was planning on using some Ferrite beads, inrush limiters, to allow the filaments to get going first. But I have been looking at slow start switches, relays, etc. When I become confused I'll be sure to chime in