So I'm going to build a switch box to switch between my CDP, Phono, and Reel to Reel (yet to be aquired). It will also have a switch to shift my main speakers between the Home theater and my tube amp. While in idea central (the bathroom) I had a "great" idea. Why not use one of the switches poles to change between glow tubes to indicate which component is selected. I'm thinking of using a 120v isolation transformer and a few diodes for the b+. The switch would select beween dropping resistors, then the VR tubes, followed by a some sort of current regulator to draw the proper current for each tube. The switches for the inputs and outputs would be totally passive, and the tubes just for show.
Here is the qwestion, what should I use after the tube? All I would need is something that could handle more than 5ma or more than 10ma depending on the VR tube. Would an LM317 be sufficient?
Here is the qwestion, what should I use after the tube? All I would need is something that could handle more than 5ma or more than 10ma depending on the VR tube. Would an LM317 be sufficient?
I don't think you need any load after the reg tubes.
Just size the resistor(s) so that the current is within the tubes spec's.
I did that on an amp I was tinkering with,just for show.One side-benefit was that it helped to keep the B+ from soaring at switch-on,before the power tubes warmed up.
Just size the resistor(s) so that the current is within the tubes spec's.
I did that on an amp I was tinkering with,just for show.One side-benefit was that it helped to keep the B+ from soaring at switch-on,before the power tubes warmed up.
Merlinb said:Since the indicator circuit is entirely separate from the audio you don't even need a transformer, you could power them directly from the mains live, as long as you're using an earthed metal chassis.
This is a terrible idea. The transformer is there for your safety which is particularly relevant on something you are likely to touch.
athos56 said:would a Nixie tube rigged to show 1 to 3 be cooler....
Yes.
Yeah I remember that the usage of raw 120ac wasn't smart.
So for the nixie.
170vcd to a 18k anode resistor (tube) then a cathode resistor on the pin of the numeral I want lit. Any idea for the value cathode resistor? I found the anode resistor value on a few schematics but most have the cathode going to a controller.
So for the nixie.
170vcd to a 18k anode resistor (tube) then a cathode resistor on the pin of the numeral I want lit. Any idea for the value cathode resistor? I found the anode resistor value on a few schematics but most have the cathode going to a controller.
It only got a bad name from the days of un-earthed metal chassis radios and so on. I guess a plastic ABS enclosure would be safer still, though. Lots of comsumer gear rectifies the mains, there's no great harm in it provided that circuit is not electrically connected to the audio circuit in any way.dsavitsk said:This is a terrible idea. The transformer is there for your safety which is particularly relevant on something you are likely to touch.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Tubes / Valves
- Switch box using VR glow tubes