XY-FZ35 - Inexpensive Electronic Load

RE: XY-FZ35 - Inexpensive Electronic Load

shabaz — Thu, 30 Sep 2021 17:05:12 GMT

Hi Frank,

Great investigation and photos! It's always impressive how much can be obtained for little outlay.. although it has its limitations but maybe it's useful for battery discharging/battery performance measurement (i.e. LiPo or something, where it wouldn't require to discharge to low voltages).

RE: XY-FZ35 - Inexpensive Electronic Load

genebren — Thu, 30 Sep 2021 15:54:26 GMT

Great Blog Frank!

This is an interesting device and it nice to see that you were able to get the serial interface to work. This could be handy device for testing, but I really would need higher current range for my immediate needs.

Well done!

RE: XY-FZ35 - Inexpensive Electronic Load

dougw — Thu, 30 Sep 2021 15:33:12 GMT

Decent price. Thanks for posting your findings. It seems viable for quite a few applications and it is useful in the sense that I would usually be reluctant to spend more for a test load. I have spent more than this making variable test loads for USB power supplies.

If someone wants to get ambitious they could capture the step response.

RE: XY-FZ35 - Inexpensive Electronic Load

scottiebabe — Thu, 30 Sep 2021 12:35:11 GMT

That is a really nice find.

This will always be the case using a Darlington pass element, it will saturate at 1Vbe + 1Vce sat approximately 1V at moderate currents. You could replace the TIP122 with a logic level NFET (though running them in saturation isn't ideal).

One could replace the current shunt with a higher value resistor, but then the display current would be off by the same factor inversed.

Looks like a basic lm324 constant current source.

Is the fan temperature controlled?

RE: XY-FZ35 - Inexpensive Electronic Load

rsjawale24 — Thu, 30 Sep 2021 10:22:28 GMT

I did try to make one. But often the DIY one costs much more than these inexpensive Chinese electronic items.

For example, recently I was looking for a SMD practice board on Banggood. Later, I thought why not to make a PCB myself? You can get 5 PCBs for 2USD from JLCPCB.

But when I calculated the shipping it was around 27 USD (Fedex) to India (Add 10 USD more for customs). Then buying 30 pcs each of SMD caps (0402,0603,0805), resistors (0402,0603,0805) and SOT packages, cost me around 300 INR ~ 4 USD

DIY Cost = 2 + 27 + 10 + 4 = 43 USD

SMD board (with Components from banggood) = 500 INR + 200 INR shipping (direct mail) = 700 INR ~ 9.43 USD

RE: XY-FZ35 - Inexpensive Electronic Load

Andrew J — Thu, 30 Sep 2021 08:58:47 GMT

Worth $18 for the LCD, rotary encoder(?) and knob. I’m sure the case would be useful too. The DC load function is a nice freebie. I’m pretty sure you could develop your project to fit in that case and have a better test instrument.