I want to build a fun project. A voltage meter for 0-12vdc that shows on a couple seven segment displays. I don’t want to mess with code or Arduino etc. Plain old digital design. Reasonable to build. Appreciate any design help. Thanks

 

When you say, "shows on a couple of seven-segment display," does that mean that you are only interested in displaying the voltage to the nearest 1 V (i.e., being able to display 0, 1, 2,... 10, 11, 12)?

Break your project into blocks. What are the various tasks that need to be performed to go from an analog voltage signal to digital signals that can drive your displays? Then tackle each one of those blocks separately.

 

Have you considered using an ICL7107 or do you want to do it the hard way just using gates and flip flops ? (I.E avoild using counter and decoder chips.).
Les.

 

There are voltmeter IC devices, at least there used to be. I bought one 30 years ago and never used it. They may still be available. OR the TS could build a voltage step A/D converter using a few LM339 comparators, and then a diode array to drive the digits. That would certainly be a fast A/D converter.

 

When you say, "shows on a couple of seven-segment display," does that mean that you are only interested in displaying the voltage to the nearest 1 V (i.e., being able to display 0, 1, 2,... 10, 11, 12)?

Break your project into blocks. What are the various tasks that need to be performed to go from an analog voltage signal to digital signals that can drive your displays? Then tackle each one of those blocks separately.

I imagine 4-6 displays. Possibly voltage by the tenth. From say .1v to 12.0v.

 

I imagine 4-6 displays. Possibly voltage by the tenth. From say .1v to 12.0v.

So... what are the other displays for? If you want to display voltage in one-tenth volt increments up to 12.0 volts, why do you need more than three displays?

You need to come up with firm specifications on what you want/need this thing to do. That doesn't mean you can't change your mind as things progress, but unless you have a pretty firm starting point for what you want to achieve, you will just flounder around as people have to guess what you do and don't want or need.

 

So... what are the other displays for? If you want to display voltage in one-tenth volt increments up to 12.0 volts, why do you need more than three displays?

You need to come up with firm specifications on what you want/need this thing to do. That doesn't mean you can't change your mind as things progress, but unless you have a pretty firm starting point for what you want to achieve, you will just flounder around as people have to guess what you do and don't want or need.

If I knew exactly what I needed I wouldn’t ask for assistance. A functioning voltage meter. If possible no microcontrollers. I want a fun project to build. Thanks for the comments and I’m sure I can get some help or not. I’m appreciative either way

 

If you are wary about getting into microcontrollers, building an Arduino voltmeter is an excellent introduction. For the input (to measure the voltage), you'll learn about Analog-to-Digital converters and for the output, I suggest using a (28 pin) 4-Digit 7-Segment display to learn how to multiplex over 11 GPIO pins instead of 28.

Of course you can buy a display module that communicates over UART, SPI or I2C which are also a lot of fun to tinker with. But programming your own multiplex algorithm is in itself a wondrous thing to behold. You can certainly design one using logic chips or analog IC's but that is a tedious effort with many bugs to potentially iron out.

I think starting with an Arduino Uno gives the best of both worlds. You'll get a crash course in programming with a high likelihood of success and accuracy. You can also measure arbitrarily high voltages using voltage dividers.

On the other hand, doing it all from scratch without a microcontroller is quite the project regardless of skill. If you go that route, you're in for a lot of troubleshooting and probably some ruined IC's. I've seen many failed designs on the internet that drove the creators mad. At the very least, you must begin with a well laid out plan (and budget) because there are a ton of factors.

 

If you do a search on ebay for ICL7107 you will find both the bare IC and the complete kit of parts to build a digital voltmeter.
Les.

 

Certainly the very first step in any construction project is in deciding just what you want to build! First the general idea and then the more specific details. It is like building a wooden box, in that first you must decide the size, before cutting any wood.
For a volt meter, first some specifications, then a circuit design, the parts, then finally assembling it.

 

If you do a search on ebay for ICL7107 you will find both the bare IC and the complete kit of parts to build a digital voltmeter.
Les.

You know, I had heard of that IC and spent some time looking but aside from finding several variations in the schematic world I found no kit and that would be great. Possibly would you have a link? Thanks!

 

Here is a link to the ebay results of an ebay search for ICL7107.
Les.

 

Hi Ican,
Check out this PDF.
E