AVC is a voltage going negative as a radio is tuned. There is very little current available and would require an amplifier to control LED's.
You could use a 6E5 or 6U5 tube by just wiring it to the radio. A 6AB5 would be necessary for AC/DC radio with 150 ma tube filaments.
Norm
:Does anyone have plans for an easy to make tuning indicator that could be connected to the AVC bus on a tube radio?
:Possibly using one or more LED's?
:Thanks,
:Jim
:
:
There are several LED drivers available, you would need to invert the AVC signal to drive a positive bar graph. You might want to consider measuring the Voltage across a cathode or screen resistor in a stage that is controlled by the AVC, and a screen resistor would have B+ on it. Maybe a small resistor in the IF amp cathode, and some op-amps to invert it and drive a LED bar display?
Lewis
PS Maybe bypass the cathode resistor with a small cap to keep the gain up.
LL
::
::
:
:
marv
:::Hi
:::
::: AVC is a voltage going negative as a radio is tuned. There is very little current available and would require an amplifier to control LED's.
:::
::: You could use a 6E5 or 6U5 tube by just wiring it to the radio. A 6AB5 would be necessary for AC/DC radio with 150 ma tube filaments.
:::
:::Norm
:::
::::Does anyone have plans for an easy to make tuning indicator that could be connected to the AVC bus on a tube radio?
::::Possibly using one or more LED's?
::::Thanks,
::::Jim
::
::
::There are several LED drivers available, you would need to invert the AVC signal to drive a positive bar graph. You might want to consider measuring the Voltage across a cathode or screen resistor in a stage that is controlled by the AVC, and a screen resistor would have B+ on it. Maybe a small resistor in the IF amp cathode, and some op-amps to invert it and drive a LED bar display?
::Lewis
::
::PS Maybe bypass the cathode resistor with a small cap to keep the gain up.
::LL
::::
:First off, thank you for your reply's.
:Norm, yours is the most historically accurate but more than what I had in mind.
:Lewis, your reply perhaps sounds closer but I would need actual plans, part list etc.
:Maybe there is another solution?
:It seems as though that as my ears age it get harder to tune my radios accurately. I usually run an AVC lead out to the back of the chassis and I can use my VOM to help in tuning but what I was hoping for is some type of small (cheap) indicator that could be wired and discretely mounted on the back of the cabinet, visible from the side while tuning.
:Thanks,
:Jim
:
:
:
Marv,
I wouldn't use an analog meter unless it is a VTVM, which is perfect for reading AVC Voltage, having a -DC position and 11 megs input resistance, you can just tweak those little adjustments and watch the meter rise when you go in the right direction. Heath, Knight, PACo, and others sold a jillion kits in the fifties, many still can be obtained at a good price.
Lewis
:
::::Hi
::::
:::: AVC is a voltage going negative as a radio is tuned. There is very little current available and would require an amplifier to control LED's.
::::
:::: You could use a 6E5 or 6U5 tube by just wiring it to the radio. A 6AB5 would be necessary for AC/DC radio with 150 ma tube filaments.
::::
::::Norm
::::
:::::Does anyone have plans for an easy to make tuning indicator that could be connected to the AVC bus on a tube radio?
:::::Possibly using one or more LED's?
:::::Thanks,
:::::Jim
:::
:::
:::There are several LED drivers available, you would need to invert the AVC signal to drive a positive bar graph. You might want to consider measuring the Voltage across a cathode or screen resistor in a stage that is controlled by the AVC, and a screen resistor would have B+ on it. Maybe a small resistor in the IF amp cathode, and some op-amps to invert it and drive a LED bar display?
:::Lewis
:::
:::PS Maybe bypass the cathode resistor with a small cap to keep the gain up.
:::LL
:::::
::First off, thank you for your reply's.
::Norm, yours is the most historically accurate but more than what I had in mind.
::Lewis, your reply perhaps sounds closer but I would need actual plans, part list etc.
::Maybe there is another solution?
::It seems as though that as my ears age it get harder to tune my radios accurately. I usually run an AVC lead out to the back of the chassis and I can use my VOM to help in tuning but what I was hoping for is some type of small (cheap) indicator that could be wired and discretely mounted on the back of the cabinet, visible from the side while tuning.
::Thanks,
::Jim
::
::
::
:
: