All Tube Dekatron Spinner Problems

[Thomas Kummer]

Hi, I’m trying to make Threeneurons all tube variable Dekatron spinner. I got everything I need aside from the INS-1, I tried to short the two wires that connected to it, but the Dekatron wouldn’t spin. Would this schematic work without it? Or, do I have to have an INS-1, or some other neon lamp there. I’m trying to do this with a GS10D(Purple Dekatron) the last time I tested the tube (Plasma ball) it worked fine. However, I have noticed that the base is loose on it now. I tested the voltage at the Dekatron anode and cathode(s) and got 450v.

[robin bussell]

On 13/04/2019 18:46, Thomas Kummer wrote:
> Hi, I’m trying to make Threeneurons all tube variable Dekatron spinner. I got everything I need aside from the INS-1, I tried to short the two wires that connected to it, but the Dekatron wouldn’t spin. Would this schematic work without it? Or, do I have to have an INS-1, or some other neon lamp there. I’m trying to do this with a GS10D(Purple Dekatron) the last time I tested the tube (Plasma ball) it worked fine. However, I have noticed that the base is loose on it now. I tested the voltage at the Dekatron anode and cathode(s) and got 450v.
>

I'm no expert but I'm pretty sure that INS-1 is being used to form a
relaxation oscillator so you won't get any movement without it.


Cheers,
Robin.

[Thomas Kummer]

Thanks I had s feeling that it was important.

Sent from my iPhone

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[Thomas Kummer]

Should the Dekatron still glow?

Sent from my iPhone

> On Apr 13, 2019, at 14:05, robin bussell <ro...@cqr-ltd.com> wrote:
>

[Jon]

On Saturday, April 13, 2019 at 7:22:09 PM UTC+1, Thomas Kummer wrote:

Should the Dekatron still glow?

The INS1 is used as part of a relaxation oscillator to generate guide pulses to step the tube, so if that were the only issue, yes the tube should still glow.

However, the GS10D has different operating characteristics than the neon-based tubes that Mike designed the circuit for so at the very least the anode resistor will need reducing (because the GS10D operates at a higher current than those tubes). I've never built this circuit, but a priori I wouldn't assume it would work - the GS10D needs a minimum 440V anode to cathode voltage to strike - not sure this circuit delivers that?

Cheers,

Jon.

[Thomas Kummer]

I measured 448V anode to cathode, and changed the anode resistor to 220K. I’m starting to worry that the tube may be bad. I tested it with a plasma ball and it lit up. However, the base is now loose on the tube, and I don’t have the plasma ball with me at the moment. 

Sent from my iPhone

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[Dekatron42]

If they have become slightly out-gassed or cathode poisoned they need more than 450V.

Nominal voltage is 475V in the datasheet and they need more than that - I have a few that work well when driven at 550V and one that worked well closer to 600V but not at nominal voltages.

/Martin

[Jon]

Mmm yes, quite right. At the absolute minimum striking voltage the formation of the glow will be slow (potentially many seconds), ambient light dependent and these days pretty uncertain as the tube will not likely conform to specs after such long storage (we know that GS10D and similar tubes degrade in storage - what Martin is referring to as outgassing). When testing GS10D I run them up to 625V (transiently) before deciding whether or not they're dead or dying.

I doubt the loose base is the issue. Most dekatrons with loose bases just have a bit of failure in the cement that holds the base shell onto the bottom of the tube - it's not directly involved in the integrity of the glass envelope per se. Nothing that a judicious drop of glue can't stabilise...

I'd suggest debugging the circuit on one of the tubes that Mike designed it for, and then adapting it to your GS10D.

Cheers,

Jon.

[Thomas Kummer]

Actually I found an INS-1, and when I attached the INS-1 I got one cathode to light up on the GS10D. I’m thinking that the problem now is the cathode resistor, now I’m trying to figure out which one that is.  

Sent from my iPhone

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