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

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.

[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.

[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.

[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

[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

[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.

[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.

[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

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

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 ??

[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.

[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

Why is that a problem? Aren't things made to be used?

I doubt I'd use it or the Eico that often anyway, my DMMs are quite a bit more convenient. However it is nice that analog VOMs can be attached to monitor a voltage or current without worrying about battery life...

[SM-Piyes90]

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

The small one I have is an AW Sperry brand SP-5A. I never thought of it as a clone of something else but it could be, no clue. Other than its size and limited scales, it works fine... just need better probes...

Just an advice , don't measure high voltages or currents , as this will degrade your VOM's lifetime.

[eccerr0r]

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

The small one I have is an AW Sperry brand SP-5A. I never thought of it as a clone of something else but it could be, no clue. Other than its size and limited scales, it works fine... just need better probes...

[SM-Piyes90]

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

The current pass seems very in line with my 50-year old Eico 555 with only 3 resistance modes. At Rx1 stage I think both of these analog meters should be able to turn a small hobby motor. I was just wondering how it got 12V, but 9V+2x1.5V is pretty normal. Reason why I asked is my dad's VOM had a custom battery in it, and I don't recall what it was. It apparently was also the sole battery in the design for Rx1 to Rx10K unlike the Eico that uses different batteries for different modes.

I think my small VOM is probably the same or a clone of the one you have... Not sure who was the OEM though, probably a lot of clones floating around.

The original brand is SANWA ( japanese brand ) , replica is sunwa like senz's one .

[eccerr0r]

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

The current pass seems very in line with my 50-year old Eico 555 with only 3 resistance modes. At Rx1 stage I think both of these analog meters should be able to turn a small hobby motor. I was just wondering how it got 12V, but 9V+2x1.5V is pretty normal. Reason why I asked is my dad's VOM had a custom battery in it, and I don't recall what it was. It apparently was also the sole battery in the design for Rx1 to Rx10K unlike the Eico that uses different batteries for different modes.

I think my small VOM is probably the same or a clone of the one you have... Not sure who was the OEM though, probably a lot of clones floating around.

[senz_90]

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

Yes, 120mA in Rx1 is three orders of magnitude larger than the 65uA used in Rx10k.

I haven't had way too many analog VOMs to check, I remember my dad's VOM was wired in reverse as well as my AW-Sperry miniature analog VOM (that uses a single AA battery for its lone Rx1K mode). The Eico 555 is actually correct for whatever reason.

What kind of battery supplies 12VDC in your analog VOM? The Eico uses a D-cell and four AAAs. I suspect the AAA's will die drying out before its energy expended at 65uA.

For big VOM is use PP3 9V battery and 2 AA (each 1.5V). Rx1, Rx10, Rx1k produce 3VDC output and Rx10k is 12VDC. Anyone using this analog VOM on my town and it is popural here.

For the small one it is just use a single AA battery inside.

Maybe I will try to measure the current. I think my VOM couldn't make a motor run when set to Rx10k instead Rx1.

[eccerr0r]

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

As I know, analog VOM is common to have reverse polarity probes. red is negative and black is positive. Rx10k is supply 12VDC as I know, but I never measure the current. From my VOM label, didn't Rx1 have a greater current than Rx10k?

Btw anyone ever use this tester?
http://www.electronickits.com/kit/co...eas/dt100k.htm
is this good?

Yes, 120mA in Rx1 is three orders of magnitude larger than the 65uA used in Rx10k.

I haven't had way too many analog VOMs to check, I remember my dad's VOM was wired in reverse as well as my AW-Sperry miniature analog VOM (that uses a single AA battery for its lone Rx1K mode). The Eico 555 is actually correct for whatever reason.

What kind of battery supplies 12VDC in your analog VOM? The Eico uses a D-cell and four AAAs. I suspect the AAA's will die drying out before its energy expended at 65uA.

[senz_90]

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

Weird... I just measured my analog meter in resistance mode:
Rx1 - measuring 0 ohms, it passes about 120mA (uses D-cell only)
Rx100- measuring 0 ohms, it passes about 1.2mA (also uses D-cell only)
Rx10K - measured around 65 microamperes?!?! (uses D-cell and 4xAA)

Trying to measure a 1W LED, only the Rx10K (expectedly) was able to light the LED. And I'm surprised the probes are actually correct (though resistance doesn't matter, measuring diodes it would be nice if the red probe is the current source and black the sink, when measuring resistance, just to know which is which.

I've only seen one analog meter so far that was hooked up backwards...

As I know, analog VOM is common to have reverse polarity probes. red is negative and black is positive. Rx10k is supply 12VDC as I know, but I never measure the current. From my VOM label, didn't Rx1 have a greater current than Rx10k?

Btw anyone ever use this tester?
http://www.electronickits.com/kit/co...eas/dt100k.htm
is this good?