That schematic is so wrong in so many ways. You need high voltage
transistors operating the tube cathodes.
You need high resistance drving the transistor bases. You need a
buffer such as 4049 or 4050 driving the
resistor, which in turn drives the transistor base. Only then would I
dare to use the 4028....to operate the buffer, which in turn operates the
transistor base via appropriate high resistance. That is the only sure
fire way I know of to attain noise-free performance from CMOS logic
driving cold cathode tubes. That schematic there is a noisy deal.
---- Original Message ----
From: "peter bunge" <[email protected]>
Sent: 2/10/2021 8:15:21 PM
To: "neonixie-l" <[email protected]>
Subject: [neonixie-l] 8453/Z550M erratic
Using the schematic from the data sheet
This works with the count moving around but other numbers flash
erratically, especially close to the number that is supposed to be lit.
When I moved the bottom of C1 to the other side of R1 it works
perfectly. It is rock steady and does not care about line voltage or the 5v
supply (shown above as 8v but used at 5v)
If this is an error it is continued through all the documentation and
is consistent. Changing the value of C1 up and down by 10 had little effect but
a smaller C1 helps a bit. My Rst are all directly on the socket pins and the
wires are all about 5 inches long.
I have varied the line voltage with little effect.
Any suggestions???
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