Interesting approach - not seen it rigged up quite like that. Let us know 
how it goes!

My immediate question is whether there's a big enough potential difference 
between an inactive guide and a main cathode to get a reliable transfer 
forward from a deactivating G2 to the 'next' main cathode rather than back 
to the adjacent recently used G1 - 5V is much lower than the datasheet 
guide bias. Might be OK at slow stepping speeds with long guide pulses. 
Also the leading edge of your guide pulses is going to be fairly slow as 
Q1/2 come out of saturation and the guides are passively pulled down to the 
'active' voltage. Most guide drive circuits use a NPN pull-down to the 
active state which creates a sharp leading edge and then a slower return to 
the inactive state.

Jon.

On Sunday, February 14, 2021 at 7:06:28 PM UTC bung...@gmail.com wrote:

> Having finished the Amperex 8453 display I started on my Dekatron. Thanks 
> to all for the suggestions.
> I read up on Ronald Dekker's clock project 
> https://www.dos4ever.com/decatron/decatronweb.html
>  and decided against a direct drive from a 74141 because, even if it was 
> practical, it would not look as good as using all the pins. It would look 
> like the 8453 I just finished except without the number mask.
> A few quick experiments showed that a -24v power supply was needed for the 
> easiest implementation.. This is my design. I will let you know if it works.
>
> A PIC drives the circuit: it starts with Q3 off to force a start at 1. A 
> high on R3 or R4 is the same as the switches in Ron's test circuit placing 
> -24v on the guides. As my PIC sends the BCD for the other displays and 
> clocks the E1T it will generate the sequence to advance or retard this 
> Dekatron..
> [image: Dekatron Circuit.jpg]
>

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