A nifty component checker

OK, I was buying some crap precision electronic stuff on Ebay and the seller also listed these little gizmos:

http://www.ebay.com/itm/261527017059?ru=http://www.ebay.com/sch/i.html?\_from%3DR40%26_sacat%3D0%26_nkw%3D261527017059%26_rdc%3D1

Runs off a 9V battery. Pop a part into the ZIF test socket or hold it to some SMD pads on the circuit board. Press the TEST button, and it tells you what you have. Automatically identifies transistors, FETS, diodes, SCRs, resistors, inductors, capacitors, and a lot of other stuff. Gives you the pinouts, measures relevant parameters, etc. The darn things actually work surprisingly well!

They are based on an open-siource design discussed here:
http://www.eevblog.com/forum/testgear/\$20-lcr-esr-transistor-checker-project/

The one I linked to is a little different because it has a backlit graphics LCD and draws pretty pictures of the parts it is testing. The open source designs moistly use a crude character LCD. I like pretty pictures and for $18 am willing to forgo the open-ness (well, actually it looks like the open-source firmware now supports the graphics LCD version, but it looks like it still runs it in character mode).

I came across something like that before…don’t think it was as nice as the one you found…excellent

I wonder if you could get some short thick leads with clippies on the end for the ability to test w/o having to latch into the ZIF socket

BangGood one is a kit… and it apparently comes without instructions on how to build it.

I already built a clippy dippy doo dad dohicky for mine… with not particularly short or fat leads.

So far it has sussed out all the parts I’ve thrown at it… except a tunnel diode… like you’re ever gonna see one of those… mine were smuggled out of Russia. With MOSFETS it shows gate capacitance and threshold voltage. Would be nice if it would show the Rds ON resistance. It does measure resistance down to around 20 milliohms.

Oh great now we are ALL on a list… :smiley:

Actually via way of Bulgaria… if you need some obscure, obsolete parts it’s amazing what you can find in Bulgaria.

So I could fit some wires to a plastic tweezer so they stick out at the end, and a use that to measure stuff while on the board? Nice device!

Does it do cap’s? I’d buy one for that alone.

http://www.fasttech.com/product/1493603

So you just poke any pin anywhere in the socket, and it just knows? Sure looks that way on the pictures. If so, that is one magic gizmo.

Yes, you stick device into the socket or onto the SMD pads, press button, voila… it tells you what the device is, its pinouts, and relevant values for that type of device. And yes it does caps (gives ESR for larger value caps). The latest open-source firmware has a mode for testing caps in-circuit… not sure how well that works… the surrounding components can affect things.

Beware that when testing caps that the cap must be discharged before connecting it… otherwise it can fry the processor (max input voltage is 5V). Caps can range from 30 pF to around 0.2F The newer open-soruce firmwares can go a little lower on the cap values.

It does not do low value inductors very well.

That’s how it starts, a few obsolete parts from Bulgaria, then the drugs, then the weapons and human trafficking. It just seems to snowball until governor Perry comes and threatens to cut your state funding. Beware TP…

Are new FW updates released for end-users to flash? I see its got an ATmega on it so we should be able to flash it with our USBASP’s and AVR dude right?

Yes… I’m not sure if .HEX and .EEP files are released since there are sooo many options you can enable. You may need to compile the code yourself. And you do have to burn both the code and eeprom files. into the chip

I did discover something a little annoying about mine… it won’t always power on with a brand new battery in it. The screen just flashes when you press the button. This could be related to a known issue with setting the brown-out detect level to 4.7V… supposedly a lower BOD threshold cures the problem.

Well, I’ve already mod’d mine. When fish8840 (does that translate as eats lotsa fish-heads?) redesigned the circuit, he made a mod to the power on/off circuitry. The board is supposed to totally disconnected itself from the battery when it turns off.

Well, fishboy messed that up… there is a voltage divider made up of two 47K resistors that cuts the battery voltage in half so that the processor can measure the battery voltage. The way he did it, that divider is always across the battery drawing a parasitic 180 micro-amps of power (drains battery in 3 months).

By moving the input of the voltage divider to the input of the voltage regulator (i.e. after the transistor that isolates the battery from the voltage regulator) the voltage divider only draws power when the board is on.

As far as the board not turning on with a fresh, quality battery… a 2 ohm resistor in series with the battery is enough to avoid the problem. Or one could probably short the battery for a few seconds to drain the “new” out of it.

Ok, did another mod. Replaced the 78L05 voltage regulator with an LM2936 low dropout/ultra low standby power regulator. Current draw went down around 30%. Also no more problems with it not staring up with fresh batteries…

Will this tester tell you if the component is bad?

If it tells you the compoenent is not what you think it is, then yes.

I hear helicopters…oh…a knock at the door, be right back :stuck_out_tongue:

and/or WAY out of spec

put a 4.7K resistor and it tells you 3 meg….hmmmm