Electronics > Beginners

Convert one output into another for 7 seg. display

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soldar:

--- Quote from: Spemo on June 18, 2019, 07:52:14 pm --- it's a clock circuit designed to be a clock - for seconds, minutes, hours. it counts in decimal, basicly what you see on a normal digital clock is what it's actually counting. makes some nice noises... sure a lot of relays, but alt least you know by the noise if just a minute went by or an hour...
--- End quote ---

Again, if you get it to count in BCD it will be much simpler.

pwlps:

--- Quote from: Spemo on June 18, 2019, 06:31:36 pm ---hmmm, are there any chips that are easily compatible with each other, without the need for an inversion stage?

--- End quote ---

I'm not sure, the priority encoders IC I saw are active-low I/O (but maybe I didn't search enough).

Otherwise you can have everything done with a simple 20pin PLD like the ATF16V8CZ.

Edit  Oops, maybe not, I think only 8 inputs can be configured as combinatorial-only.  But a slightly bigger one like the ATF22V10CZ or ATF750C should do.

mariush:
Any reason why my microcontroller idea would be bad? Seems like you could easily get a 16/24/32 pin micro in DIP package and reduce a lot of wires and diodes.

To reduce the number of diodes and wires ... you could use common cathode diodes, maybe have for example tiny PCBs made with 2 common cathode surface mount diode packs mounted on a tiny pcb with 0.1" headers

ex. 4 diodes common cathode, 20 cents @ 100, 7 cents each in 3k pieces: toshiba-semiconductor-and-storage / 1SS309-TE85LF
or bav700 : diodes-incorporated/BAV70DV-7
or bav70hdw, around 13 cents for 4 diodes : diodes-incorporated/BAV70HDW-7


Make for example individual parts with 4 diodes per pack... you'd need 2-3 per segment, so you don't waste much.

You could easily design a PCB and use v-scoring to cut small rectangles out of a bigger pcb... you'd save space by not using thick individual diodes and maybe you could use ribbon cables with 0.05" (1.27mm) spacing instead of 0.1" to reduce space used and make it easier to keep track of wires, instead of soldering individual wires.
 


David Hess:

--- Quote from: Gyro on June 16, 2019, 10:26:16 am ---You could go old school and program an 8 bit parallel EPROM to do it. 10 or more address inputs and 8 outputs to drive the segments (and dp if you want).
--- End quote ---

A PAL or similar can also be used; they were practically designed for this sort of application.  I have seen both used and with one extra input, the outputs can be inverted to support both common cathode and common anode displays.

For artistic stuff though, I like the idea of a diode or even better, a transistor array.

floobydust:
Nuts and Volts magazine Transistor Digital Clock project used 556 of 1N4148 diodes, mostly for the combinational logic.
It looks like a lot of soldering.

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