Really lost trying to figure this out

[jpanhalt]

No, the addon board is required for reading anything more than 200mV
The add-on board has a precision resistor divider network on it for being able to select 20V, 200V, 500V


Dave

I think you missed the last few words of my sentence.

John

 

[lostintranslation]

since I have to order the add on board anyways, I will return the cx102b for the cx 102a, with the add on board, it should work. still have a question for you guys tho please.

The volt meter I am using currently, that works even if it bleeds the caps slightly, has three leads. read supply pos, black supply neg, and yellow that goes to the first cap pos post. these CX102 meters are showing 4 connections, where would the neg to be read get wired in? ???

 

[lostintranslation]

well it doesnt really matter 9V or 5V supply you need to sort out how to get either of those

AND SERIOUSLY you are going to have to make the effort to start drawing and using proper circuit diagrams
its extremely difficult for people to understand what you are doing and what mistakes you may have made in a construction
without being able to see the actual schematic of what you have built

You are really going to have to take the time to catch up with the rest of the world, else you are going to find your electronics
experience very difficult into the future

Dave

sorry about the lack of circuit diagrams. I built a house once without a blue print or plans, yep, not the ideal way to go for sure. thanks for bearing with me and the help. (edited: WIHTHOUT, lol)

 

[davenn]

tis early morning ... still waking up


D

 

[lostintranslation]

I believe both meters need the add on board. It is possible to get the datasheet for the chip on that board and rewire it yourself. I did that, but I suspect that is not something you want to get into.

Have you tried your alligator-clip method of welding? I have concerns over that working. The CD welder I made, used a high-power SCR for firing. I also had abut 400,000 to 800,000 µF for my capacitors. The equivalent series resistance of the capacitors will limit your welding current.

Most important, 35V can be lethal. I know it is less than the 45 to 50 V usually considered lethal, but that threshold is highly variable. One can find case reports of welders being killed by lower OCV's. The cases I found were from China.

John

yes, it works fine, no problems other than the slight .1v per second bleed down. no problems, and the ability to toggle the uF helps for small to large wires.

as far as lethal, I guess it may *possibly be, but with such a small DC short burst, I was counting on it not being lethal. the charge button makes the contact to allow the charge to build up, and it is broken as soon as you let off the button, so... i made one from a disposable camera flash prior to this one with the board and display, got zapped by it a couple times, and while it was annoying, no burns or anything.

 

[jpanhalt]

Why return the meter you have? It allows common ground.

The meter I used was from MPJA, and I am assuming they are effectively the same. Have you checked MPJA.com to see what it has?

John

 

[lostintranslation]

Why return the meter you have? It allows common ground.

The meter I used was from MPJA, and I am assuming they are effectively the same. Have you checked MPJA.com to see what it has?

John

was returning the meter I have because it might be easier for someone like me to get the 9 volt supply figured out, than it would to understand how to get a 5 volt exact supply. I am going out on a limb here and assuming someone will say "voltage divider, but since I don't have the vocabulary or circuit diagram knowledge to be able to do that....

also, I still don't really understand how to wire in 4 wires, like I said, the meter I am using only has 3 wires, 2 supply, one to the cap being measured, where would I wire in the 4th wire on this new meter?

 

[jpanhalt]

That's what no common ground means. You wire two wires to the meter's supply voltage. Then two wires (+ and - ) to the voltage you want to measure.

The very inexpensive meters at Harbor Freight have an internal battery (2 wires) and two wires for the voltage you want to measure.

Personally, I would go the common ground route. You can use 4 LiMH cells for approximately 4.8 volts to run the meter you have.

John

 

[lostintranslation]

thanks. I appreciate you taking the time to explain that to me.

so, both wires going to the signal source, the + and - both go to the positive + cap terminal? or just the positive goes to the positive, and the negative goes to the same ground as all the rest of the weld circuit?

also, I found this on MPJA, would it work the exact same way as the other add on board?

http://www.mpja.com/Scaling-Board-for12205_06_07_08-Panel-Meters/productinfo/12209 ME/

 

[jpanhalt]

We have not actually seen your circuit. In the one I built, the SCR was in the ground return to the capacitors. Cannot answer your question with certainty without that information. However, measuring the voltage across the capacitors would be fool proof.

There is a high likelihood it will work, as it seems most of these import meters are the same. But, the pin out may be different and without the schematic, one can't determine that. So, it would be a risk. If you are returning the meter you have to Jameco, why not just buy the whole kielbasa form MPJA?

John

 

[jpanhalt]

BTW, here is a description of how th change the range of the MPJA meter:

The panel meter selected was the Digital Panel Meter (MJPA, cat. #910-4053). This meter is relatively inexpensive and operates from a common ground with the voltage being measured. The product is shipped with instructions that include a schematic. The meter includes a 7660 voltage converter, which provides a negative supply and enables the common ground. As shipped, the meter has two ranges, 0 to 199.9 mV and 0 to 19.99 V. Neither is optimal for this application. It is possible to design an external divider on the spot welder main PCB, but it is effectively easier and results in a meter with a more linear response to simply modify the meter circuit board. I found it easier to remove the PCB from the meter case for soldering, but that is not absolutely necessary to do. The main IC in the meter is an ICL7107CPL. Carefully remove this chip and identify the two range resistors (See: A, labeled R990K and R10K) on the PCB. The schematic that is sent with the meter shows them as R4 and R9. I did not find those numbers on the PCB; instead, the PCB was labeled with the values. Those resistors are replaced with 1% resistors of 1X10E6 ohm and 1X10E3 ohm, respectively, to give a X1000 range (i.e., 0 to 199.9 V). The attached Figure shows the modified board. I used 1206 resistors, because that is what I had on hand; 805's will also fit. NB: The seven segment LEDs are soldered to the back of the PCB, so one doesn’t need to worry about the flexible contacts sometimes used today to connect LCDs and the like.

Replace everything and use the trimmer (See: B) to recalibrate the meter, if necessary.

And a picture:


John

 

[lostintranslation]

We have not actually seen your circuit. In the one I built, the SCR was in the ground return to the capacitors. Cannot answer your question with certainty without that information. However, measuring the voltage across the capacitors would be fool proof.

There is a high likelihood it will work, as it seems most of these import meters are the same. But, the pin out may be different and without the schematic, one can't determine that. So, it would be a risk. If you are returning the meter you have to Jameco, why not just buy the whole kielbasa form MPJA?

John

thanks.

the circuit is wired up exactly as that wiring diagram indicates. not sure info is missing? not trying to be difficult, I really don't "get it", not being flippant at all.

my concern is this, the negative black wire after the caps combined with the positive lead is what does the welding, bring the two charges together. I was a little leery of connecting the meter positive to the positive cap, and then connecting the neg from the meter or anything to the negative cap terminal....

MPJA has the module, but I didn't see the LED with the impedance this has. admittedly, I didn't look very hard for the meter, got tunnel vision on the add on board. if this meter works with an add on board, I just thought returning this one and buying another was a null and moot point?

couldn't help but notice your location. I grew up in Canton, OH.

 

[lostintranslation]

BTW, here is a description of how th change the range of the MPJA meter:


And a picture:
View attachment 10638

John

a picture is worth a thousand words to me, so thanks for the pic.

 

[jpanhalt]

thanks.

the circuit is wired up exactly as that wiring diagram indicates. not sure info is missing? not trying to be difficult, I really don't "get it", not being flippant at all.

The circuit you showed has a separate LED supply. That is what I was talking about. What is that supply? Can you just change the regulator to a 5-v version?

I am currently living very SW corner of Lorain County, where Lorain, Huron, and Ashland meet.

John

 

[lostintranslation]

The circuit you showed has a separate LED supply. That is what I was talking about. What is that supply? Can you just change the regulator to a 5-v version?

I am currently living very SW corner of Lorain County, where Lorain, Huron, and Ashland meet.

John

Yes, I put the LED supply separate, but it doesn't have to be. it is a 9 volt battery as is now. I thought that keeping the supply to the LED and the LM board would make it easier? the power to the LED is a 9 volt battery harness/snap. that's it. 9 v battery to a switch, the switch to the LED, and the ground wires. ???? I have a AA version battery holder on hand to go to two AA for combined voltage if that helps...? or 4 AA's, whatever it takes to get the supply right for the new panel meter and add on board, no problem.

 

[lostintranslation]

to use the CX102B with common ground after the add on board comes in, I will need to wire in a 10k resistor between the power source negative and the signal source negative? what is the 0.1uF opposite the 10k resistor on the CX102B spec sheet diagram? that's pretty much why I didn't get the common ground version, wasn't sure how to wire it in, the 9v seemed pretty straight forward....gotta laugh at myself daily.

 

[jpanhalt]

to use the CX102B with common ground after the add on board comes in, I will need to wire in a 10k resistor between the power source negative and the signal source negative? what is the 0.1uF opposite the 10k resistor on the CX102B spec sheet diagram? that's pretty much why I didn't get the common ground version, wasn't sure how to wire it in, the 9v seemed pretty straight forward....gotta laugh at myself daily.

I have no idea what the capacitor and resistor are for . That arrangement of a capacitor and resistor is often used for filtering, but if the meter is actually common ground with the voltage being measured (red line), then obviously that filter does nothing. Sometimes, these cryptic datasheets lose a lot in translation.



When a meter needs to read its own supply (i.e., common ground), one needs a negative voltage generator (I comment on that in the quote I posted).Those supplies are capacitor switching supplies. Maybe that resistor/capacitor is needed to filter noise from the negative supply for the meter? Don't know, and haven't thought about it much. If you go to a separate battery supply for the meter, it won't matter.

John

 

[lostintranslation]

I have no idea what the capacitor and resistor are for . That arrangement of a capacitor and resistor is often used for filtering, but if the meter is actually common ground with the voltage being measured (red line), then obviously that filter does nothing. Sometimes, these cryptic datasheets lose a lot in translation.

View attachment 10644

When a meter needs to read its own supply (i.e., common ground), one needs a negative voltage generator (I comment on that in the quote I posted).Those supplies are capacitor switching supplies. Maybe that resistor/capacitor is needed to filter noise from the negative supply for the meter? Don't know, and haven't thought about it much. If you go to a separate battery supply for the meter, it won't matter.

John

thanks, I was trying to keep on point with this project today, but got burned out, so, powered down the computer and relaxed for a little while. appreciate all the help, insight and info. I will get the add on board for the meter, and see where that takes the project. I hate asking the suppliers questions, they almost always just say "yes, that's what you need" and move on to the next customer. I asked about the resistor and cap in that diagram mainly because if I understand what it does, I can usually catch on, but with it just thrown in the spec sheet, kinda leaves me wondering why they didn't built it into the meter board, or the add on board. at least I can get resistors and caps off the shelf locally, no need to order and wait. thanks again. I'll try and update this when the add on board comes in. cheers.

 

[lostintranslation]

thanks John, the add-on board came in today, bingo, no bleeding, steady reading. thanks for all the help, appreciated it. cheers.