DIY DMM Leads help

[kosPap]

hi all!

I need to make a series of custom DMM Leads.
Both sets must be short ones, like 10 inches at most.

One set will be with SMALL alligator clips. That is easy. Cut down existing ones to length, solder clips, done!

But what about the second set that neeeds to be short and with regular leads?
I have looked at ebay and saw no DIY kit.
An idea is to use banana (speaker) jacks at the DMM end, but how I am to connect the leads wire to them?
What kind of contact resistance do the banana jacks have assuming a maximum of 10A current?

I am open to suggestions...TNX, kostas

 

[uk_caver]

When you say 'regular leads', is that leads with probes on the end?

4mm plugs tend to connect to wires either by screw or solder connections.

If you're going to be making high current measurements, have you thought of making an external shunt, and using the DMM to measure the voltage across it (what's the smallest voltage range of your DMM) ?

Advantages:

Test leads could be soldered direct at the shunt end, avoiding 2xplug/socket resistance (both croc clip and probe leads could be soldered on, using whichever is best for a given scenario.

For resistance-critical measurements, leads could also be soldered at the target end.

A screw terminal block could be fixed to the shunt to make it easy to connect it directly into wiring.

Lower overall resistance than some DMM (depending on DMM voltage ranges).

High current lead lengths can be kept short while allowing the DMM to be a convenient distance away.

If making power measurements, the shunt can be left in circuit while doing voltage readings, making the results more accurate, since voltage readings are done with the circuit in the same state as when current readings were made.
If you were interested in measuring driver efficiency for switch-mode drivers, a second meter (or a second shunt) would allow for input and output currents and voltages to all be measured in the same circuit state.

Cheap DMMs often seem to have 200mA and 10A ranges but not a 2A one - with a 100mOhm shunt and a 200mV range on the meter, you could get a 2A range giving more precision than the 10A one had (just need to remember the decimal point is in the wrong place).
On my meter with 2A+20A ranges, I use the 2A one a lot, and very rarely use the 20A one.

(I'm really starting to wonder why I haven't bothered making myself one yet...)

 

[louie]

You can buy DIY banana plugs and test lead wire, or buy ready-made test leads in many lengths. One of the standard industrial manufacturers in the USA is Pomona, which is sold by many of the distributors that sell LEDs! I do not follow the "audiophile" or "Carsound" markets, but they seem to also have banana plugs for DIY. Pomona rates these for 15 amperes. Contact resistance would probably depend on the socket used. Their website is pomonaelectronics.com

 

[kosPap]

Uk caver...that is a good idea...

i think someone suggested the method before but definetwely not using the shunt word...
i had to do a search on the shunt method and i feel i ahev grasped it....Tonight it is Tv & Beer night so I will have sometime to try it out adn figure a way to have it semipermanently installed.

hopefully my DMM -even though it is cheap-reads correctely (I get the expected readings from AMC7135 drivers) but i amy be off with my driver testing rig which i never use with XML currents. This way I can check the accuracy of
http://www.candlepowerforums.com/vb/showthread.php?214469-My-Driver-and-LED-testbed-IT-IS-READY-NOW

luie....unfortunately no leads at various lengths in my countries market. banana plugs are the screw type only...I will ahve to see if I can solder wire on them cos the wires are too thin to trust the screw holding them reliably over time.

 

[Vortus]

Home made current cable:
2 banana plugs and 2x20cm thick wire (As thick as can be mounted in the banana plugs). A shop with high end car audio probably has the parts.
You do only use plugs on one end of the wire.

Cut from another thread about leads.