Useful cheap small tester...

[Mark Hennessy]

Rather than the low Vf, it might be confused by leakage. I'd be pretty surprised if it didn't do Shottky diodes, given how prevalent they are today.

The Peak Atlas DCA copes well with Ge devices, but then it does cost about 5 times more than these

[Nick]

If you look at Section 7, "Known Problems", of the original manual I posted in http://golbornevintageradio.co.uk/forum/...6#pid46386, you will see that even the fully adapted original hardware has problems with some germanium devices, and these Far Eastern knock-offs, wonderful though they are, are built to a price, not quality, so do not include what are generally considered mandatory updates to the hardware.

I would read the section on known issues with the clones, Section 2.5, and see if those can be retrofitted to the eBay cheapies...

[jimmc101]

I have the 'Banggood' version (see post 96) which appears to have all of the mandatory hardware updates.

I have updated the firmware to v1.11k and it will read germanium devices

For an OC71 as a transistor
   
   
And as a diode (C-B shorted)
   

I've also tried 1N34 and OA91 diodes which were OK, however a power diode (Vf 150mV, Ir 1250uA) gave the 'No or damaged part' message.

Jim

[Old Sparky]

I've just bought one of the Ready made testers off eBay ( the same one as in your posts #91 & 92, Alan. It arrived yesterday, after only 7 days in the post from Shenzen, China. I haven't tested it yet, but may well fit it into a plastic box as in your post #98. Point taken about the display, but the one on my tester is larger (ca. 58 x 38mm overall, and is set well to the left of the PCB as viewed from the front, so that it covers the top LH fixing hole, so I'll have to lift it clear in order to be able to pass a screw through the hole, or maybe fit screw with spacers through the bottom of the box, and not put a nut on the top LH one. As to the ZIF socket, I'm not sure whether to remove it or not, but will almost certainly fit three seperate terminals wired to the pads in any case. The PCB may well fit into that case sold with the self-assembly tester, but as tthe display with the latter appears to be smaller, the hole for that would need enlarging.

[Yorkie]

You can't box up these testers without removing the ZIF socket because the lever of the socket won't be able to go far enough down to properly grip the component wires placed in the socket holes for testing. If you do remove the ZIF socket, don't attempt to do it with the socket intact by using a solder sucker on the PTH PCB.  Instead, as carefully as you can, destroy the plastic casing of the ZIF socket to reveal the individual pins, then grip each pin with forceps and apply the soldering iron on the underside of the PCB until the pin can be pulled free.

The solder on the PCB is lead free and if you attempt to use 60/40 solder to make any joints you'll be in for a merry dance if it mixes with lead-free. (Don't ask me why I know that!).

The tester that I got is the same as Alan's. I've given the dimensions of the display cut-out and spacing of the front panel holes in post #102.

Handy little gizmo, with few vices - mainly,  it seems not to like low value inductances which it thinks are resistors, and certain other components will report no or damaged part. The readings that I obtain compare well with other more expensive test gear. (Well 'expensive' by my standards as a hobbyist - Peak Atlas and AADE). I used mine today to check out a bandpass filter on an Ekco AC77 that I'm sloooowly restoring.  It happily measured a coil with 2.8 Ohm resistance, identified that it was an inductor and reported its inductance as 0.16mH. It also reported that an 800pF silver mica cap in the filter was 797pF. I checked these readings with other test gear, which came up with the same readings.

I'm impressed with an 80 year old cap that's still accurate to below 0.4% tolerance!

Have fun with the tester.

[Old Sparky]

Since post # 114, I tested a couple of known faulty AF117s (with the usual 'tin whisker' problem), albeit with a PP3 which only measured 6.8v on the tester!0 Both were shown only as diodes, despite my twice making sure that the b, c, and e leadouts were securely in 3 different terminals of the ZIF socket. Regarding said socket, I may well retain it, and add 3 seperate terminals for test clips. I've seen a complete, boxed version on eBay which has a slot in the side of it's case to allow the ZIF lock/release lever to be operated, so I may be able to do something simiar when I make a case for my tester, which will probably be a plastic box. One thing,not related to the above, is that i tried to print the part of the eBay listing with the specifications of the instrument, and in the 'print preview' that section was omitted. Why this should be I know not

[AlanBeckett]

Don't know if the attached is the right one but I guess they're all much the same.

Alan

   

[Yorkie]

Always intriguing to try to translate 'Chinglish' into English:

This precautionary statement from the kit version for example:

"When measuring 1 uF non-polarity capacitance, attention to short-circuit capacitance between two feet and put off storage of electricity when measuring capacitance, otherwise may damage the instrument, if measuring instrument with electricity is easily to make display show CELL and can't  use normally, we are not responsible for this kind of situation, what you can do is replacing the chip, it is important to note, please!"

Noted!

I think they're trying to say that even non-electrolytic caps of 1uF can hold a charge, so make sure you discharge the cap by shorting the leads (the 'two feet') before connecting it to the tester.

Not trying to belittle them - their English is far superior to my non-existent Mandarin (or whatever), so credit where it's due.  

These little testers, of whichever type, have to be the best ten quid Chinese 'takeaway' that can be had.

[Old Sparky]

Thanks, Alan, for that Instruction sheet. You're right in that those instructios are very similar to thosefor the tester I bought. Handy to have the spec. in print

[Old Sparky]

I have now built the tester into a small plastic box (obtained from Maplin), retaining the ZIF socket, althought I may add other sockets in parallel to this in the light of experience. The most difficult part was cutting the rectangular holes for the display & socket, and I need to add a clear perspex 'lens' for the display, so it's currently a 'work in progress', but a useful piece of kit nonetheless. I may post some pictures later.