OT: neon lamps from previous post

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Thu May 6 11:40:27 1999

>> Flip flop should be easy too. This one looks rather like an ECL logic gate:
>>
>> +V DC
>> |
>> <
>> >
>> <
>> >
>> |
>> +--+--+
>> | |
>> (:) (:)
>> | |
>> A--+ +--B
>> | |
>> > >
>> < <
>> > >
>> < <
>> | |
>> GND GND
>>
>> Pull A to ground. Lefthand neon lights. Voltage on right hand neon too low
to
>> maintain discharge and it goes out. Same works for B - RH neon lights and
>> voltage at the common anode too low to maintain LH neon, which goes out.
>
> Nope! If left is not list then there is no current flow across the
> resistor. To ignite the left lamp a voltage (negative maybe 25V) would
> have to be applied at A. To extinguish left a voltage of +25(or more)

I see what you mean. (Careless of me!) A and B would definitely need pull-ups,
but I think it could work. The initial current when you apply the negative
pulse to one input should drop the voltage at the common anode sufficiently to
extinguish the other neon.

> volts would have to be applied. Generally this kind of logic is pulse
> coupled using transformers or capacitors. Note a bistable was done in the
> case mentioned with one Neon.
>
> Doing ascii logic from telnet seesion is far to slow for me to give a
> complete circuit.

Don't post a circuit yet - I want to think about the one-neon flipflop.
Theoretically possible, anyway - the two states are on and off (now why does
that sound vacuous?).

Philip.
Received on Thu May 06 1999 - 11:40:27 BST