LRC + ESR meter kit - built

[johan]

I'm making an own thread for this meter (mentioned here)

I needed a good, wide range LC meter and I have also always wanted an ESR meter. I then found this page, and ordered the kit.

It has L, C, F and ESR and is microprocessor based. The kit doesn't contain any box, nor any external hardware like switches, wires or battery connectors. It contains the display with cable and connectors, PCB and every component to assemble on the PCB.

Short specs:

C: 1pF – 100000 μF (accuracy in 1-100 pF: <10%, from 100 pF: <5%, after calibration: <2%)
L: 10 nH – 30 H (accuracy: 10-100 nH: <10%, from 100 nH: <5%, after calibration: <2%)
F: 0.1 Hz – 8 MHz (accuracy: 0.1-1%, 5V logic, 5-30V signal is measurable as well at 1-10 mA current restriction)
ESR: : 0.000 Ω – 30 Ω (resolution for 0.000-1 Ω range : 3 mΩ, for 1-30 Ω range : 0.03 Ω, accuracy: 1-5%, from 1 μF, after calibration: <2%)

To ensure a good accuracy, it should be calibrated against known components, alternatively measuring a few of the components before assembling the meter. I chose to measure the precision polystyrene capacitors (C3, C4) and the two PET capacitors (C12, C13) that forms the inductance measurement bridge in the meter. I also measured the resistors for the capacitor measurement.

It was easy to assemble and calibrate. Calibration is entirely in software.

It is recommended to have separate terminals for the ESR measurement. I haven't decided yet what to use. Maybe some kind of small, bent copper sheets.

Next thing is to put it in a case. Here is a couple of pictures:

[gray5596]

Looks nice! I didn't see a price on the web page. Do you remember what you paid for it?

[johan]

50 €, which included shipping. The knobs, switches, wires, battery, measuring probes etc. was another 25 € from my local supply store. I have an old enclosure that should fit.

[johan]

Fitting into an enclosure. I figured that I will use a separate current limited terminal (with a series 5k resistor) for frequency measurement above TTL level (up to about 30 V should be safe). That's the empty hole. Four pieces of thin PCB board will have to suffice as ESR measurement terminals for now.

Continued...

[VictoriaGuy]

Originally Posted by gray5596

Looks nice! I didn't see a price on the web page. Do you remember what you paid for it?

I got the following email response when I inquired about cost:

"I have some KITs. It's exact content can be found on my Webpage:
ESR meter LC LCF LCR LCFESR L/C L/C/F inductivity capacity frequency capacitor measurement instrument AVR ATMega8 Mega88P


The meter KIT is 43 Euro + 2 Euro Paypal cost + 5 Euro postage
(registered mail) from Hungary to abroad.


I can send full version software burnt in ATMEGA88PA-PU for 15 Euro +
1 Euro Paypal cost + 2 Euro normal postage.


Best regards, Le Hung"

I notice that this is another seller adding on 'PayPal cost' to the price, contrary to the seller agreement with PayPal. It seems to be getting very common.

[johan]

Originally Posted by VictoriaGuy

I notice that this is another seller adding on 'PayPal cost' to the price, contrary to the seller agreement with PayPal. It seems to be getting very common.

Which seller agreement? In this case, the agreement is between you and the seller. Paypal is only money transfer.

[VictoriaGuy]

Originally Posted by johan

Which seller agreement? In this case, the agreement is between you and the seller. Paypal is only money transfer.

No.

PayPal User Agreement (the one you clicked 'Accept' when you set up your PayPal account.....)
"4.5 No Surcharges. You agree that you will not impose a surcharge or any other fee for accepting PayPal as a payment method. You may charge a handling fee in connection with the sale of goods or services, as long as the handling fee does not operate as a surcharge and is not higher than the handling fee you charge for non-PayPal transactions."

[johan]

OK. At least in the past, there were no restrictions to this in various EU countries, but maybe that has changed.

[johan]

Now I have had time to test the meter a little. Calibration is tricky in ESR and Inductance mode. This is because of the resistance of the test leads and the clips.

When zeroing the meter in ESR and inductance mode, a minimal resistance in the test leads and a good connection in the clips are critical. It takes quite a while to fiddle with the leads to get the meter zeroed. Once zeroed, at least in inductance mode, the measurement results are consistent and seems accurate. The ESR mode is more unstable using the test leads. The zeroing is also stored in the memory so when turning the meter on next time, you don't have to zero it again. But when changing the test leads, you have to repeat the procedure.

Using the directly connected test connector for ESR makes zeroing easy and the measurement seems a lot more stable than when using test leads. In fact I would call it very good and perfectly usable. This is understandable, because with the test leads I am using, the resistance in the clips and the test leads is about 400 mΩ (includes the resistance path through the rotary switch). This is compared to the directly connected ESR connector.

I would like to get some quality test leads and clips, preferably short, but I don't know what to get. It is critical that the clips have a very good connection to the measured object. Maybe I should solder directly a short set of test leads and only use the banana plugs when needing longer cables.

[johan]

The meter is ready. I made two short test leads that make measurements more stable in L and ESR mode.