Ideas for PW and PE readers designs

[cdog]

Okay, so if you've recognised the initials, you're probably an old timer like me, one who bemoans the irresistable march of the PIC brigade!
We mainly belong to an age where we made our circuits from scratch, (and took great joy from a successful gizmo..but rarely enough joy to actually box it up and USE the thing), and to press 'salvaged' parts into a use for which they were not designed was a thrill in itself.
I'm coming to the point now, so put down the Phyllosan, and tune in and turn on. (I always thought that the hippies had that wrong. Supposedly you would have to 'turn on' before you could 'tune in'. After a suitable interval whist the tubes heated up first, of course!) But I digress. I have about me two identical front panels with 4 digit 7 segment LED displays. These are driven from a MC14499P chip. I want to make them become a 30volt voltmeter, and a 3 amp ammeter respectively.
Any circuit ideas chaps. cdog.

 

[eem2am]

Re: PW and PE readers

it sounds like a cop-out, but the book from Babani on PIC circuits has a good circuit for an easy PIC voltmeter.

You can easily drive 7seg LEDs from PICs. so i would get a PIC with an ADC in it and just use that.......to reduce the number of lines...connect the inputs to the 7segs to the same PIC ports and separately activate each 7seg (like multiplexing)

..........you bacically switch the 7 segs on/off so fast that they look on all the time.

assembler is easiest if youre beginning PICs......just have a huge look up table and give out the right codes to the seven segs when your AD gives you respective values.

 

[cdog]

Re: eem2am

Thanks for your reply mate, but I know that I COULD use the standard 7107 if I just wanted to make a meter. However, to a lot of us, simply building an off the peg circuit is fine if it's needed for a specific and urgent job, but real satisfaction comes from 'going there, seeing it, and buying the T shirt'. Again, thank you for your input nontheless. cdog.:|