Useful cheap small tester...

[richard296]

yorkie i'm waiting for my gizmo to arrive. you say no instruction. the pics on ad aren't clear 6 socketts no 11,12, 13, i see how to test caps and resistors. is it trial and error with trannies etc or have you the worked out the formula. thank you in advance.

[camallison]

With transistors, you just put the 3 leads to 3 sockets, obviously middle to middle, and then it tells you what each lead is as well as characteristics. Leadout identifier!

Colin

[Yorkie]

yorkie i'm waiting for my gizmo to arrive. you say no instruction. the pics on ad aren't clear 6 socketts no 11,12, 13, i see how to test caps and resistors. is it trial and error with trannies etc or have you the worked out the formula. thank you in advance.

Hi Richard.

The one that I got has five sockets - two for T1 and T3, and one for T2. For components with two lead-outs - resistors, diodes, capacitors, you conect to any two of the sockets and it will display on the screen. Hence, for a diode say, it matters not which way around you put it into any of the three sockets - if you put it into 1&2, 1&3, 2&1, 2&3, or whichever way around you put the diode. It will come up on the display and show the connections and readout. Same goes for capacitors, inductors or resistors – any two of the three test leads will suffice. If you wish to test say 2 caps, two resistors or two inductors in series, across T1,T2 & T3, it will show you the individual readings and the total.

If you connect a transistor, you connect it to the three leads any way you wish and the readout will identify which lead is which – say 1,2,3, = B,C,E or if an FET say 123 = D,S,G.

Incidentally, as an aside, the bare unit has the facility to test SMD devices but if you box it up as I did, you lose that facility, but as I don’t use SMDs it’s not an issue for me.

I know that there are those who think that the accuracy of test gear is directly proportional to the price of that gear, and that it therefore follows that even second-hand complex test gear many years old is infinitely more accurate than anything cheap and modern from the Far East which they write off as cheap tat. Fine, if that’s what they think, but I dismiss such views as ill-informed and without any underpinning proof to support their assertions.

Quite apart from that, on some forums, beginners asking advice as to what equipment to buy are often advised to look out for certain makes of highly complex test gear which may be unreliable, will certainly be un-calibrated, and will have features they don’t need and wouldn’t know how to use.

There are few occasions when accuracy is needed, such as caps in tuned circuits, but most components in equipment we work on will have originally have been +/- 20% tolerance when new. Hence, a 10K 20% resistor could be within spec if it was between 800 Ohms and 1,200 Ohms, or a 470pF cap could range from 376 to 564 pF. A 15mH choke could range from 12mH to 18mH.

Though I’m financially secure and could buy expensive test gear if I wished, I’d consider it a waste of money and quite unnecessary. All of my test gear is either home made, or cheap, and it serves my purposes fine. As far as this little ‘multi-tester’ gizmo is concerned, to illustrate the point, I’ve tested a few components on several different (cheap!) meters with similar results – namely a 100pF capacitor, a 4700 Ohm resistor, and a 15 mH choke. I also tested a J310 JFET and the cheap gizmo correctly identified it as a JFET, identified the lead-outs and gave other information. I tested the J310 on an (expensive!) aging Peak Atlas ‘DCA50’ Transistor Tester which claims to test MOSFETs (not JFETs AFIK) but never has and unsurprisingly, it said ‘no valid part found’. I believe I could send it back to Peak for a software update, but it’s not worth the effort - I rarely use FETs so it’s not an issue for me.

The bottom line – for me at any rate - is that the little cheapo multi tester is a great little device which I’ve had for getting on for a year now and to date, it hasn’t skipped a beat.

For wht it’s worth, the readings I obtained on various bits of test gear were:

4700 Ohm resistor:

‘Gizmo’ 4712 Ohms.
Maplin Multimeter 4k7

15mH Choke:

Maplin Multimeter 15.11 mH
All Digital Electroncs meter 16.04 mH
‘Gizmo 16.9’ mH (Also showed the resistance 291R).

100pF polystyrene cap:

Maplin PG105 Cap tester 102.8
All Digital Electronics meter 107.4pF
Cheap Far East cap kit meter 100pF
‘Gizmo’ 101 pF

Though slightly different readings were obtained, in part that could be due to the inductance/capacitance/resistance of the test leads of the various meters. The Maplin cap meter and All Digital Electronics meter and the cheap Far East kit cap meter have the facility to null out stray capacitance, and the resistance of test leads can be checked by shorting the leads on the low Ohms range.

I’ve attached a few pics hurriedly taken on the bench top.

Others will remain convinced that you get what you pay for, will favour 'famous name' brands, and that cheap test gear is inaccurate, unreliable and of no use to hobbyists such as ourselves. Fine, I’ll let them hunt around on internet to find out how to repair their faded Fluke multi-meter displays, in company with thousands of others:

http://shop.flukerepairkit.com/

http://www.ebay.com/itm/Fluke-88-Repair-...0795694815

No thanks - best multi-meter I've got is the £10.00 Toolzone jobby.

Ho hum.

[pwdrive]

"I know that there are those who think that the accuracy of test gear is directly proportional to the price of that gear"

Me included, cheap tat scopes v Tektronix.


"And that it therefore follows that even second-hand complex test gear many years old is infinitely more accurate than anything cheap and modern from the Far East which they write off as cheap tat. Fine, if that’s what they think, but I dismiss such views as ill-informed and without any underpinning proof to support their assertions"

Here's my proof, my old Avo analogue meter still works, I have never had to repair it, my cheap tat DVM packed up, there is little chance of repairing it so on that basis my Avo is infinitely more accurate than my cheap tat DVM.

Lawrence.

[Refugee]

Posh gear is well worth restoring if it looks tatty and in need of a bit of TLC.
I wanted an analogue meeter with a high terminal resistance a couple of times over the years and such an item appeared FOC but looking sad.
It is an Avo and came up looking good and all the readings track those of modern kit.
http://golbornevintageradio.co.uk/forum/...p?tid=3358&pid=33981#pid33981
At least with the modern cheap stuff you can afford to buy a new one if it goes wrong.

[pwdrive]

It is, I have an AVO CT378 sig gen, it did develop a fault, no AM modulation, a capacitor across the inductor in the AF osc had gone short circuit, a quick and easy fix. The scale is adjustable too, only goes down to 2 Mhz though, never the less very accurate against WWV etc. Accurate attenuator too.

Lawrence.

[richard296]

interesting stuff. you've done a grand job of housing the esr meter. I had wondered if extending the terminals would alter the readings. obviously not enough to worry about otherwise you would not have done it. I had took on board regards the small meter terminals. did you solder extension wires to the small terminals. thank you in advance. haven't received my meter yet. richie

[Nick]

...Here's my proof, my old Avo analogue meter still works, I have never had to repair it, my cheap tat DVM packed up, there is little chance of repairing it so on that basis my Avo is infinitely more accurate than my cheap tat DVM.

Using that reducto ad absurdum logic, my old watch that stopped 2 years ago is more accurate than the very best atomic cesium fountain national physics laboratory reference clocks... twice a day

[pwdrive]

Absurdum logic indeed, especially when the clocks go forward.

Lawrence.

[Yorkie]

interesting stuff. you've done a grand job of housing the esr meter. I had wondered if extending the terminals would alter the readings. obviously not enough to worry about otherwise you would not have done it. I had took on board regards the small meter terminals. did you solder extension wires to the small terminals. thank you in advance. haven't received my meter yet. richie

Re the test leads, although I fitted quite short ones, I don't think longer leads would make an appreciable difference unless you wanted to accurately measure low value caps - say below 47pF, when the test leads might introduce some stray capacitance of perhaps 5pF or so. I've got three cap meters in which I can zero the display to null out any stray capacitance in the leads - it's usually about 5pF. For other measurements - ESR, higher value capacitors, inductors, resistors, transistors, the length of the test leads should have no appreciable effect.

The holes in the small test terminals on the PCB are similar in size to 'turned-pin' IC sockets and are designed so as to grip the wires of components pushed into them. I wouldn't on any account solder to these terminals - I just pushed short pieces of solid tinned wire about the same thickness as component ends such as resistors, which are typically 0.6mm diameter, then soldered those leads to the front panel sockets.

Had I been a bit more fussy I could have used three terminals from a 'header strip' like those in the attached pic, but solid wire is fine.

I tend to use this little tester more than other separate bits of test gear as it's so handy being multi-functional.

As others have said, you can carefully solder leads across the solder pads of the on-board push-button test switch to extend the wires to a front panel momentary push button switch.
(See Joe's pic at post #33).

I guess that in terms of frequency of use of test gear, for me, the top three that I use are:

1) My trusty £10.00 Toolzone multi-meter.
2) The multi-function cheap and cheerful tester that this thread is about.
3) A signal injector/tracer based on the Velleman K7000 kit.

Total outlay for these bargain basement items - about £30.00.

There's nothing I could buy at any price which would do the job any better.

Hope that helps Richie - best of luck with the meter when it arrives!