Author Topic: Project help Needed Please, portable electronics circuit, DIY multimeter  (Read 629 times)

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Offline projecthelpTopic starter

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  • Country: england
Hello all,

I am a college student from the UK and as part of my course i have to do a project, I have been given a project to do which is to Design a portable electronics circuit that can be used for training.  It must be;
Able to measure current, voltage and resistance.
Operate on 10 Volts DC, but plugged into the mains. (You will need to rectify and transform it down.)
Have a maximum of 5 resistors that can be in series, parallel and complex.
I have a tight budget and any help would be welcome,
Thanks
 

Offline bob91343

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Not enough information.  You could use any cheap VOM to accomplish this.
 

Offline jeroen79

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Yes, that sounds like an VOM.
You'll need an analog meter for that. And suitable a rotary switch.

In what ranges must it measure current/voltage/resistance?
Any requirement on accuracy/precision?

The max 5 resistors requirement sounds a bit silly to me.
I guess the teacher wants you to work out some fancy switching arrangement to get various ranges.
 

Offline OM222O

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It's nearly impossible to use only 5 resistors. for a similar project I had to use 11 resistors just to get 6 ranges! You can spread out the ranges but that'll cost you accuracy. You also need at least 1 resistor as a shunt for current. even using analog meters, you only have 4 resistors left which is only enough for 1 voltage divider + 1 non inverting amplifier. so possibly 3 ranges (divided, amplified, divided * amplified) or maybe 4 if you directly buffer without amplification / division.
You can forget any digital circuitry for that matter too because ADCs need filtering which means more resistors.

Like others mentioned are there any accuracy constraints?
Even if you bother to do the mental mathemagics to figure out the overall gain and actual voltage / current, you'd be lucky to get any real accuracy out of a system like that
 


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