Digital Weighing Machine

[Meesam]

Hello to everybody there.
I am working on a project that is to make a weighing machine with digital ouput on 7-segment leds.
The main parts should be:-
1. Force measuring components (typically load cells)
2. Getting the ouput from the load cells. (analog values)
3. Analog to digital conversion (ADC804 or ADC808)
4. Binary to 7-segment decoder. (still searching for good one.)

The most important thing is that I want to do all this project without using any MCU or MP.

Now my main problems are follows.
1. To select a right kind of ADC and most importantly to give the signals to ADC without using any MCU.
2. Right kind of binary (from ADC) to 7-segment decoder.
3. Some techniques to display values on multiple 7-segments as we will be using only one ADC.

Regards to everybody.
Please anybody interested do contact me with useful ideas.

 

[Nigel Goodwin]

Presumably this is a school assignment?, no one would try and do it without a micro these days - it's just so much cheaper and easier.

I suggest you look at 7107 digital voltmeter IC's, that would probably be the easiest method without a micro?.

 

[Meesam]

Please guide me about the real-time circuits and related theory. Its an assignment of cost. But the main target is doing all this with using any MCU. I know quite well how to work with MCUs but it is a target and challenge to control the whole apparatus without any MCU. Please guide me about this if you can.

 

[Nigel Goodwin]

We aren't here to do school assignments for people!, it's your assignment, get out there and do some work on it!. I've already given you a suitable clue!.

 

[dknguyen]

I would say sigma-delta ADC is probably best for something like weighing...

You are going to have a hell of a time coming up with your own decoding circuitry. It's gonna take a lot of discrete components. If you don't want to use a uC, at least use an CPLD or something so you can "code" the hardware you need rather than having a ton of discrete components lying around.

The decoder you want is dependent on the output of your ADC (as I am sure you have realized)- which means you aren't going to find one unless it was made specifically for your ADC. Then it also needs to do exactly what you want (that's called an ASIC and it's made very specifically for one application and you aren't going to find one or be able to get one made).

Or you could try what Nigel said and look at voltmeter components- but I don't know anything about those.

 

[rajat]

ya even i feel the same dknguyen, the use of mc is the good option , without which the complexity increases like hell, and interestingly the descrete comps ll add much of the delay and this may be a prob
i feel ...