How can I control a 4026 counter chip from my raspberry pi?

Question

I have a 4026 counter chip controlling a seven segment LED display.

The current set up is every time I press a button it advances by one digit on the display. See circuit below.

This circuit runs on 9v so I haven't been too adventurous in my testing from fear of frying the Raspberry Pi.

How can I control this with an Raspberry Pi, regarding 9v vs Raspberry Pis 3,3 volt ?

Example circuit.

Possibly but it's hard to tell from your description as the current circuit could do anything. 9V is not good for the Pi but an opto-isolator can cure that if you are concerned A basic functional overview and circuit is at petervis.com/GCSE_Design_and_Technology_Electronic_Products/… and you would replace the switch to pin 1 with an isolated signal from the Pi with a pulse twelve of a min of 100ns based on components101.com/sites/default/files/component_datasheet/… and 10v Please add more details to post. — user115418, Nov 9 '20 at 0:04

Mats Karlsson · Accepted Answer · 2020-11-09 07:26:19Z

3

Since there are only output from the Raspberry Pi that should drive the 4026 7-Segment Counter there are only need for a driver circuit.

This can be done with transistors, MOSFETs or a driver IC.

A simpler way is to change the voltage for the 4026 from 9 volt to 3,3volt its within the IC's working parameter (3-15v).

And then replace the current limiting resistors to the 7-segment LED display to fit the new voltage.

And now you can interface the 4026 directly to your Raspberry Pi.

answered Nov 9 '20 at 7:26

Mats Karlsson

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1

I tried with 3 V but it isn't consistently bright, i ended up using 2N2222 transistors to interface. – euan Nov 11 '20 at 15:06
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@euan Nice, that is a appropriate solution. Did you change the current limiting resistor when you changed the voltage ? – Mats Karlsson Nov 11 '20 at 15:43
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@MatsKarlsson No, I mean displays with several LEDs in series, which need higher voltage regardless of the current-limiting resistors. Running a single led per segment display with 9V results in incredibly poor efficiency. – Dmitry Grigoryev Nov 11 '20 at 15:51
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@MatsKarlsson For instance SC23-12EWA is a 12V part with 4 LEDs in series in each segment (except the dot). – Dmitry Grigoryev Nov 11 '20 at 17:16
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descargas.cetronic.es/SC23-12EWA.pdf – Dmitry Grigoryev Nov 11 '20 at 17:24

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