Useful cheap small tester...

[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.