Digital Voltmeter!! on Breadboard

[4pyros]

Looking at both of them, I do not see a -5v supply in either one....? I wonder why someone mentioned needing -5v?

The 7660 makes the -5 volts that goes to pin 26 of the ICL7107

 

[KeepItSimpleStupid]

Hmm, you're right. When I said to use a -5v display I was repeating what someone else had said--I had not looked at the schematic yet. Looking at both of them, I do not see a -5v supply in either one....? I wonder why someone mentioned needing -5v?

Pin #26 is fed by the 7660 charge pump, hence -5V from the +5 supply. Easy to check with a DVM.


==

If the LED display is really suspect, then one needs to compare the datasheet for the one that's needed and try to light the display segments with the series resistor and power supply. What I asked to do as a test.

Alternatively, you can disconnect all of the segments. Leave the ANODES connected. Now connect each segment to ground through a resistor (The same one I said to test with) and each LED should light the same segment of the LED. Compare with the datasheet.

 

[remon7]

Today i will start work again .................

 

[4pyros]

good luck

 

[audioguru]

The display is supposed to be common anode. It is simple to test if it is common cathode or common anode.
The IC has a test pin #37. When it is at a logic high (it sinks 15mA!) then the display should read 1888.

Most of the schematics posted show the 10uF capacitor at the output of the ICM7660 voltage polarity converter connected with backwards polarity.

 

[remon7]

The display is supposed to be common anode. It is simple to test if it is common cathode or common anode.
The IC has a test pin #37. When it is at a logic high (it sinks 15mA!) then the display should read 1888.

Most of the schematics posted show the 10uF capacitor at the output of the ICM7660 voltage polarity converter connected with backwards polarity.

I did not get u ...what about 37 pin with Power supply !!!!! volts ??? only 37 ,,necessary about negative and positive ....

 

[KeepItSimpleStupid]

It does say 7106 but it may apply to the 7107

The second function is a “lamp test”. When TEST is pulled
high (to V+) all segments will be turned on and the display
should read “1888”. The TEST pin will sink about 15mA
under these conditions.

CAUTION: In the lamp test mode, the segments have a constant DC
voltage (no square-wave). This may burn the LCD display if main-
tained for extended periods.

 

[audioguru]

I did not get u ...what about 37 pin with Power supply !!!!! volts ??? only 37 ,,necessary about negative and positive ....

I guess you do not have Intersil's datasheet or their 8 applications notes about it.

 

[remon7]

I guess you do not have Intersil's datasheet or their 8 applications notes about it.

i did not get you..... in silly things i was failed ...

 

[4pyros]

Is it working?
Did you check the negative supply?
Did you try the test pin to test the display?

 

[remon7]

No... :'( ...I have to collect right 7 segment display same as figure(Circuit diagram).................... MAN6910 maybe.