Hi all
Does anyone have a diagram for a digital volt meter to measure from
0v - 50v DC. The only thing is the unit must be powered by the same source it is measuring. If thats not possible I can live with a seperate 9v supply.
Its quite a few years since I did anything like this so if anyone has a project that includes a pcb layout that would be great.
many thanks
My friend made this circuit, worked fine & its reading speed also superb.Here is the complete circuit with PCB.Don't know what resolution to be adjust for the PCB.
Another reason to use a ICL7106 instead of a ICL7107 is that the ICL7107 gets so hot driving the LEDs that it's internal voltage reference starts to drift.
Thanks all for your input guys. It looks as if I might be able to manage that one, and looks as if it might do the job.
Audioguru will using ICL7106 instead of the ICL7107 alter the rest of the circuit at all?
I have just also noticed that on the circuit pics that there are components other than what the pcb has room for????
Does anyone have any idea what these are for ??
Ok Eric, you lost me there, its a very, very long time since I did anything like this. I take it that where pin 21 goes to ground it needs to connected to the led's. if so where ? It looks as if it is for the minus sign ? what if I dont need the minus sign, can this be left as is?
Ok Eric, you lost me there, its a very, very long time since I did anything like this. I take it that where pin 21 goes to ground it needs to connected to the led's. if so where ? It looks as if it is for the minus sign ? what if I dont need the minus sign, can this be left as is?
hi,
No, the POL, 'polarity' is the minus sign.
On the LCD display, look at the dwg for your LCD, you will see BP pins as well as the segment pins.
They may be more than one BP pin on the LCD, they ALL must go to the BP pin of the 7106.
Another point to consider, if you are displaying 50.0Vdc, is the decimal point, these will also be indicated on the LCD dwg.
hi,
No, the POL, 'polarity' is the minus sign.
On the LCD display, look at the dwg for your LCD, you will see BP pins as well as the segment pins.
They may be more than one BP pin on the LCD, they ALL must go to the BP pin of the 7106.
Another point to consider, if you are displaying 50.0Vdc, is the decimal point, these will also be indicated on the LCD dwg.
Hi Eric.
Got it now. Many thanks.
Fingers crossed that I get it all right, otherwise I will be buying a unit to do the job. Its been about 25 years since I did anything like this.
just found a alternate chip to the 7107, its listed as NJ9202BD, as far as I can see it is pin compatable and there is a LCD variant avaliable as well, I have a PDF Datasheet for View attachment voltmeter.pdfit Hope this helps, Karl
If you use it in bright environment an LC-Display is fine. I used it to make a micromanometer and reading in completely dark air channels requires an LED-display.
Using high efficiency LED-displays the current consumed by the display is below 100mA.
I also used the same power source for the pressure sensor circuit and the DVM circuit. Measuring current the power source must be separate from the circuit to measure.
Hi to alll
I have made my power suplay and for voltmeter I use the schematic with ICL7101,and my voltmeter is suplaying with other transformer,separate from power suplay.
here is picture of my power suplay and link to voltmeter schematic: