Different between analog VOM with DVM on testing transistor or mosfet

[senz_90]

Re: Different between analog VOM with DVM on testing transistor or mosfet

That small VOM is looks fragile. I don't like use it to measure high voltage or current, I am using the big one. If I were you I don't want to try it. If I remember correctly, the small one haven't fuse at all.

Yes, the pros is we could measure voltage and current without fear of dying battery. The original brand is SANWA japanese brand and SM-Piyes90 were right, the others are clone. it seems the small one just have a 1.5V and hard to turn on the small motor, i haven't test it yet. that small one is just my beginning experience about electronic and now I am very rare to use it so I couldn't tell much.

[eccerr0r]

Re: Different between analog VOM with DVM on testing transistor or mosfet

The small one I have can only measure 250mA and 500V (which is not quite as high as the YX1000A) so it's not like I'm going to measure that high a voltage. However I have measured mains voltage with it, shouldn't be a problem except that the probe wires were replaced with sub quality cables (hookup wire instead of probe wire since I don't have any on hand).

My small one with the Rx1K will only source less than 1mA of current so it could not turn a motor. The larger meters with Rx1 that supply over 100mA should be able to drive tiny motors.

I now have a small DMM (Mastech M300) that I use instead of the small analog VOM. Unfortunately it uses those A23 cells and it's real easy to kill the battery by leaving it on... sigh.

[SM-Piyes90]

Re: Different between analog VOM with DVM on testing transistor or mosfet

That small VOM is looks fragile. I don't like use it to measure high voltage or current, I am using the big one. If I were you I don't want to try it. If I remember correctly, the small one haven't fuse at all.

Yes, the pros is we could measure voltage and current without fear of dying battery. The original brand is SANWA japanese brand and SM-Piyes90 were right, the others are clone. it seems the small one just have a 1.5V and hard to turn on the small motor, i haven't test it yet. that small one is just my beginning experience about electronic and now I am very rare to use it so I couldn't tell much.

Hi senz , i have found a cheap ( 5 USD ) chinese DMM using ICL7106 according to some sources , but is core is placed under some sort of silicon drop , do you have a way to track DT830D DMM's Microcontroller pin numbers ??

[Agent24]

Re: Different between analog VOM with DVM on testing transistor or mosfet

Check ICL7106 datasheet and reference schematics, compare with which components are connected to which pins on the COB. You *might* figure it out.

If you're trying to turn it into an ESR meter, I would say use it in conjunction with this: http://circuit-zone.com/?electronic_project=484

[SM-Piyes90]

Re: Different between analog VOM with DVM on testing transistor or mosfet

Check ICL7106 datasheet and reference schematics, compare with which components are connected to which pins on the COB. You *might* figure it out.

If you're trying to turn it into an ESR meter, I would say use it in conjunction with this: http://circuit-zone.com/?electronic_project=484

Nice one Agent , this makes thing real easy .

Edit : in witch range should i read the ESR value ? 200 OHM rang by any chance ??

[Agent24]

Re: Different between analog VOM with DVM on testing transistor or mosfet

Probably 200mV range actually.

Easy to find out by testing by measuring a low ohm resistor. That is the same way we calibrate the Blue ESR meter from Bob Parker anyway.

[eccerr0r]

Re: Different between analog VOM with DVM on testing transistor or mosfet

I think that $5 meter is another rebadge of the Mastech M830, and yes I think it does use the die of an ICL7106-clone (according to schematics). It's not a microcontroller and doesn't have many special features.

Usually the range used on the "ESR converters" are using one of the volts ranges and not resistance ranges. Staring at the schematic, it looks like it should output a higher voltage as the resistance increases. I was also wondering how it got AC needed and now see that it uses a dual rail +/- 5V supply to get the AC voltage needed.

[senz_90]

Re: Different between analog VOM with DVM on testing transistor or mosfet

Hi senz , i have found a cheap ( 5 USD ) chinese DMM using ICL7106 according to some sources , but is core is placed under some sort of silicon drop , do you have a way to track DT830D DMM's Microcontroller pin numbers ??

Yes, this cheap DMM were sold about $4 on my town. I don't have it so I couldn't see what's inside. But is this really have ICL7106/7 in there? I would like to buy it if it has, and when this failed I would scrap it around

[SM-Piyes90]

Re: Different between analog VOM with DVM on testing transistor or mosfet

Yes, this cheap DMM were sold about $4 on my town. I don't have it so I couldn't see what's inside. But is this really have ICL7106/7 in there? I would like to buy it if it has, and when this failed I would scrap it around

This one is an old dt830d model i guess new ones Are SMD based and use different IC package

Here is a picture of the old model's ICL solder holes

[eccerr0r]

Re: Different between analog VOM with DVM on testing transistor or mosfet

I haven't seen many DMMs with actual 7106 DIP in them anymore, most are surface mount dies with some sort of covering. Finding a 7107 is even more rare - I do have one in an old panel mount digital meter (200mV) but the two LED DMM's I have use the older LD110/LD111 chipset.

The last DMM I've ever seen with an actual 7106 40-DIP in it was a kit I bought decades ago, I gave it to a friend. Otherwise all these cheap meters, despite it still being a 7106 die, is just a die - and probably can't be removed from the circuit board.

[Agent24]

Re: Different between analog VOM with DVM on testing transistor or mosfet

It's called COB - Chip On Board. Bare IC die connected to pads and covered with epoxy. You could take it off but it would be hard to do anything with.

Cutting out the piece of board it's on might be usable.

You can also buy full ICL710x chips on eBay quite cheaply.

[senz_90]

Re: Different between analog VOM with DVM on testing transistor or mosfet

maybe it is quite rare to find any ICL7106 chip on this DMM. Mine DMM also didn't have any IC on them just a black circular chip like those, maybe I have to choose the other option. thank you.