matt_hau

I am trying to find a circuit for a seven segment display driven by varying dc voltage from a motorcycle gear position sensor.

It needs to be very compact as is the GIpro gear indicator oon the market. By all accounts it seems that the brains of the display driver is no bigger than the display itself.

Anyone know how this is done?

Nigel Goodwin

Probably a micro-controller?.

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matt_hau

Would a 7447 7 segment display decoder work? If so how would I turn the voltage from the bike to binary code?

rebirth of sands

i used a 4511 as a seven segment driver and it is cool....checkout its datasheet at alldatasheets and it is just a 18 pin DIP stuff....try it out

matt_hau

Thanks I have seen the 4511 decoder but from what I understand about it I still need to convert the analog signal from the motorbike into a binary code??

Brian Hoskins

That's what an ADC is for. You'll need to do some homework if you expect to be able to use one though. They're not that difficult really, but you need to understand what you're doing with them. Also you'll probably need to do some signal conditioning such that your analog output fits within the "window" of the ADC input.

Brian

matt_hau

The range of volts is 1-5DC. Can you suggest a link that will show me "signal conditioning" ? I have been searching everywhere and although I can find lots of technical talk on ADC there is nothing in laymens terms or a basic explanation of how to generate the required binary output (that I can understand anyway).

e.g. how do you create the required binary from the ADC to meet the seven segment decoder requirements? is it software or simply input voltage?

Brian Hoskins

Signal conditioning is fairly simple - you just use Op-Amps. Gain can be used to make the signal bigger if it's too small or smaller if it's too big. Then addition / subtraction can be used to "shift" the signal up or down (alter it's D.C. level) such that it fits as tightly as possible into the window of the ADC. Are you familiar with the use of Op-Amps? Do a bit of research and see what you can find out. If you're still stuck, come back and I'll post some example circuits that you can alter to suit your requirements.

7-Seg displays work on BCD. The output from the ADC will be binary - therefore you need a Binary to BCD converter like this one for example:

http://www.utm.edu/staff/leeb/DM74185.pdf

Brian