Ascel 20204 LC meter kit

[nctnico]

For an upcoming project I could put a inductance meter to good use. Because I didn't had one I went looking to see what is available on Ebay. I found several cheap Chinese multimeters but the specs where not stellar and the boat anchors where not appealing as well. I looked a little further and found this little kit:

http://www.ebay.com/itm/261114892135

I choose for an AC adapter, blue screen, tweezers and RS232 output. The USB option didn't interest me because the device can be used stand-alone.

It can measure inductors between 10nH to 100mH and capacitors between 0.01pf to 1uf. It can't be used on electrolytic capacitors. I think the bottom end of the measuring range is a bit optimistic.

I took some pictures of the assembly process:
This is the contents of the kit. It also shows the SMD tweezers. The PCB is gold plated which looks nice but IMHO hot air tin plating is easier to solder by hand. Before assembly I gave the PCB a spray of SK10 flux.

I haven't used these kind of components for a while...

Fortunately I still remembered the color coding so assembly went quick. Ascel should look at other KIT makers. The manual is a bit chaotic. The schematic, bill of materials and PCB layout are each in different chapters. I'd print them on consequtive pages.

A little oops here... I mounted to pushbuttons on the wrong side so I had to unsolder them and mount them on the proper side.

The designers also made a small mistake. With the wires connected to the screw terminal (I added the ferrules) the casing won't close. I turned the screw terminal around to make it fit.
Now for a try:

It works! I like the blue display. Its clear and easy to read. Now for a few tries. I tried some in-circuit measurements but that appeared to be tricky. Also a 100nH SMD inductor wouldn't measure. Bigger inductors (tens of uH) seem to work OK. The manual warns about trying to measure inductors with a low Q since the AE20204 uses resonance to find the capacitance or inductance values.
Time to put in the screws. I didn't bother to mount the SUB-D connector or the on/off switch. I did add some stick-on rubber feet to prevent the case from moving around.


All in all its a cute device for measuring capacitors and inductors.

[Icarus]

$50 is too much for a well know PIC LC meter
Here is the circuit
http://electronics-diy.com/lc_meter.php
This technique is fundamentally flawed. A local noise source could easily cause injection locking.

[amspire]

$50 is too much for a well know PIC LC meter
Here is the circuit
http://electronics-diy.com/lc_meter.php
This technique is fundamentally flawed. A local noise source could easily cause injection locking.

But this is a kit and nctnico was able to build it. That is fantastic - there just aren't enough good kits available now. Anyone can buy a Chinese LCR meter. Also since this is based on an opensource project, it is possible to fiddle with the code and the design. That is fantastic too.

It has data logging capability. Are there any other $50 LCR meters with datalogging?

Yes, if there is local RF close to the oscillating frequency, you could get injection locking causing an error of a few percent. Isn't this the same as the capacitance range of most multimeters? People seem to be very happy with multimeter capacitance ranges. Since capacitors and inductors usually are 5% or worse tolerance, most of the time a small error does not matter. It is still a very useful tool.