| Electronics > Beginners |
| Dirt cheap and simple scope-based component tester - curve tracer |
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| w2aew:
<shameless self promotion ;)> I posted a new video that shows an old idea for simple component testing / curve tracing using an oscilloscope and just a few components. Circuits of this type have literally been around for decades, and are often referred to as an Octopus component tester. I really don't know the origin of the name. You can Google various search terms like octopus component tester curve tracer, etc. and find dozens of variants. The video basically shows how this simple technique works, and demonstrates with some examples. Enjoy: Alan - W2AEW |
| TerminalJack505:
I love your videos! I had never heard of this circuit before. |
| Fraser:
Nice video, thanks. I first built an 'Octopus' whilst at Maritime College in the late 1980's. As you say, they have been around a long time and are often home built as so few parts are needed and they work so well on semiconductors. Whilst working for my employer I was trained to use the Huntron Tracker instruments. For those who don't know, these are an 'Octopus' combined with a scope display to produce an all-in-one instrument for testing components. The Huntron units add a little to the design by having several voltage/current ranges to suit differing scenarios. They are very useful bits of kit, especially when hunting a fault on a PCB and you have a known good PCB as a reference to compare to. I bought a couple of used Huntron HTR1005B-1S a few years ago at a very reasonable price. Prices have sky rocketed since then so the word must be out that these are good units. The Hameg oscilloscopes used to include an 'Octopus' mode in their design, named a Component Tester mode (CT for short). I have always thought them forward thinking to have done so. You can often pick up an HM203 series 20MHz CRO for a very low price or even free if you are lucky... if you do, you get a simplified version of the Huntron Tracker included for free ! Tektronix used to sell a advanced 'Octopus' I/V component tester under the model no. TR210....it was in fact made by Huntron and also sold under their model no. HTR-200. The unit was designed to connect to the TDS200 series DSO's in order to provide a component testing capability. It was far more advanced than the simple Octopus, HTR-1005B-1S or Hameg CT. I managed to pick one up a couple of years ago quite cheaply. If you see one at a decent price, you should consider buying it as it is a very refined piece of test kit with special low voltage/low current modes to suit modern low voltage MOS technology. A word of warning..... Huntron carried out tests on TTL and CMOS technology to prove that the 50V test pulse that the Tracker could generate would not destroy the component under test. Huntron advise the use of the lower voltage ranges, but succeeded in proving that the chips tested still worked. It is interesting to note that Huntron later released the 2000 series that had more ranges and lower test voltages but these are still considered risky if used on very low voltage MOS components. The TR210/HTR-200 and later models all provide very low test voltage modes for VLV MOS and even have a special range lockout function to prevent accidental activation of the higher voltage ranges. Me thinks Huntron are not confident that the latest low voltage technology will take kindly to the older Huntron/Octopus excitation voltages. Be careful regarding this point if you DIY an Octopus for use on sensitive low voltage MOS technology. The topic of this thread is 'Dirt Cheap' and none of the units I have mentioned, except the Hameg scope, could be considered cheap. A chap in the USA decided to build and market a cheaper solution. Take a look here: http://www.actracer.com/ Whilst the unit is cheaper, I do not consider it cheap per se considering the component count but then this isn't a China made unit ;) The ACtracer has a little bit more versatility than a basic Octopus and may be worth considering if the budget will stretch to it. Its certainly a lot cheaper than a new or used Huntron 2000 which it is trying to emulate. Aurora |
| digsys:
My Elektor (Heathkit) Transistor curve tracer, from 1980 I think, was my favourite test tool by far !! I had the Hamegs, but they were no where near as nice. Being able to drive a transistor to destruction, observing failure mode, then just backing off to recover ... multiple traces, sure miss it. |
| w2aew:
--- Quote from: Aurora on June 09, 2012, 11:20:07 pm ---Nice video, thanks. <<<snipped>>> Aurora --- End quote --- Aurora - awesome post, great information! I was aware of the Huntron units, and the Hameg scope with the CT option. That is similar to the Heath scope that I showed in my video, and I've also seen the same scope under other names. However, I did not know about the Tektronix/Huntron unit - and I work for Tektronix! Of course, I didn't for for them 14 years ago when this was a product. Very interesting! Thanks for watching and posting. |
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