Good information Martin. The board as described to me by Richard has the grid resistor you mention, as does mine. Certainly, if someone is wiring up one of these tubes directly - in this case as colons for example - they need to be aware if this.
> On Oct 16, 2020, at 3:32 PM, Dekatron42 <[email protected]> wrote: > > > Be careful if you decide to switch the grid electrode to ground as you might > destroy the tube if you pass too much current through the grid electrode. > Normally you should not leave the cathode floating (unconnected) while the > anode is seeing full anode voltage and then connect the grid electrode > directly to ground as all current will then flow through the grid electrode. > Always use a high-ohm resistor, usually in the megohms range, connected to > the grid electrode to limit the current (the grid resistor is then working as > a voltage dropper for the current drawn through the trigger electrode). > > There are circuits which you can design which will let the tube self > extinguish a short time after it has been triggered, this due to the use of a > capacitor across the anode/cathode in conjuntion with either an anode or > cathode resistor - some of these boards look like they have large > non-electrolytic capacitors mounted on them which could then possibly be used > for this effect. If you set the time constant short enough of this R/C > combination you can select your own frequency to drive the grid electrode > with, in effect dimming the tube depending on the frequency used. This is > commonly used in the drive stage of dekatrons with a trigger tube like with > the GTE175M and also the Z70U. > > You can read more on this in "electronic counting circuits" by J.B. Dance and > other books on trigger tubes, page 82 mentions the self extinguishing > mechanism in chapter 4.3.5 with the "40 c/s driving circuit". > > /Martin > -- > You received this message because you are subscribed to a topic in the Google > Groups "neonixie-l" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/neonixie-l/bVoCKhPv7Dg/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/42c46a0d-95d2-4179-aa54-71250a24b638n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/564F2176-332B-46D0-9EA4-E3944D091B14%40gmail.com.
