697Re: IV-17 SS kinda working!
- May 18 8:34 AMThats some progress, Simon. I'm pleased you've got scrolling to work.
I've just downloaded the same software from the files section to my breadboard and both PWM control pots work as they should. Have you tried measuring the voltage from the pots at the pic inputs to make sure it is varying as the pots turn. Maybe the frequency pot has lost it's ground connection ?
The decimal points are driven from pins 25 and 26. These are active high, so you need a suitable buffer or a pair of transistors typical of those used to drive nixie tube anodes, an MPSA42/MPSA92 pair.
I don't have the time to draw a schematic now, so referencing the schematic on the last page of this manual....
...zoom in to the top left corner and build Q9,Q3,R7,R13 for each of the two decimal point lines. Drive the bases of the MPSA42's (Q9) form the pic via a series 22k resistor (10k-33k should work). Change R13 to 100k and try that. Instead of driving a nixie anode you will instead connect the line to the decimal points of one group , right or left. Probably R22 should be much lower, like 1k. If it doesn't work first time try raising the 10k value of R7 until it works. I used to use the transistor pair, before I used the transistors for something else which is why the values are sketchy.
As for the clock function, that function got backbenched and needs some work still. It might work if you use decimal numbers where yoiu see numbers in the command structure but I can't say for sure what will happen, if anything.
--- In email@example.com, "shklaw75" <shklaw75@...> wrote:
> Hi Chris,
> Thanks for the explanation on the reasons behind the use of dec/hex in the commands and the details of the message scrolling commands, working very nicely now.
> Tried the freq pot while the duty cycle pot was set to 50%, no change to the output freq. I am using linear pots, so the middle is in the middle!
> Another thing I would like to get working is the decimal points. Any chance of a schematic for wiring them up, or an updated schematic of the IV-17 smartsocket for the manual?
> Much appreciated.
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