Poor man's Peak DCA55?

[vizcities]

After a few (read: three in a row) likely Tayda-related vero non-starters, I started to feel like I should invest in some variant of the Peak DCA55; I had this vague suspicion that my caps (and maybe my resistors?) were dead, off spec, or some calamitous mix of both. Not having the cash for an actual Peak, I snooped around eBay and landed on this ~$15 guy:

http://www.ebay.com/itm/Cased-12864-Mega328-ESR-Meter-Transistor-Resistor-Diode-Triode-Capacitor-Tester/201871158671?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It arrived yesterday and, as far as I can tell, it's a winner. It precisely detected ESR and some modest variations in some 22uF elec Tayda caps I had lying around, as well as the size/tolerance of a few resistors and the name/designation of a couple transistors. The internal library is open source, and there seems to be a small connector onboard for possible firmware updates. I bought the "boxed" version and I would suggest that others do the same, as it's otherwise just an LED screen and a PCB connected by a cheap ribbon cable. It runs on a 9v battery and goes to sleep when you're not using it. As far as provenance goes, I think it's somehow related factorywise to the inexpensive oscilloscope people were talking about a month or two back - like the oscope, it has a number of "clones"/rebadges kicking around the web.

Hopefully this will be useful to someone! I've been hankering for a Peak since I started this hobby, but the "Mega328" is a perfectly serviceable alternative (for now). 

[culturejam]

That's similar to the one I have. It's more than reasonably accurate for most things. Just keep in mind that transistor leakage is relative to the test conditions of *that* testing device. So you can't just compare leakage numbers with other test devices in an "apples to apples" way.

In my view, leakage testers are useful for getting a feel for *relative* leakage between parts in a given set of transistors.

[reddesert]

I have one of those (unboxed). It works pretty well. I've used it to check some components, test some old electro caps in a solid state amp (they were fine, the problem was a cold solder joint), etc.  To add to what CJ said about transistor values, it correctly identified JFETs but the voltage and current values are different from the ones I measured with the ROG FET matcher, and not precise enough for real FET matching, so no shortcuts there.

I just posted something similar on another thread: I have built quite a few veros with Tayda components and they all worked fine. When I have a problem, it's been things like unsoldered pins that were hard to see, components off by one hole, bad connections, stuff like that. Vero is very flexible but provides ample opportunities to mess up. Audio probing and voltages usually help me isolate the problem.

[chromesphere]

That's similar to the one I have. It's more than reasonably accurate for most things. Just keep in mind that transistor leakage is relative to the test conditions of *that* testing device. So you can't just compare leakage numbers with other test devices in an "apples to apples" way.

In my view, leakage testers are useful for getting a feel for *relative* leakage between parts in a given set of transistors.

Agreed.  If anyone wants the "ridiculously indepth" explanation, heres my take:

[stringsthings]

I've got the version that Tayda sells.   It's great for double-checking resistors, caps, diodes.
I don't really trust the hfe readings for bjt's but it's good for verifying pinouts on any transistor.

The tayda one doesn't have a case.  If I get another, I'll get one in a case.  Prevents the battery from flopping around
and prevents the bottom of the PCB from shorting or just getting dirty.  ( I put a piece of tape on the bottom of mine ... cheap solution )

[BillyBoy]

Note that the makers of the DCA55 and DCA75 apparently thought it would be a good idea if they used different transistor test parameters for those two units.  The DCA55 results are more comparable to other methods and will give you results in line with the rules of thumb for hfe and leakage in various fuzz circuits, etc.  The DCA75 tests with higher parameters that will generally give you higher HFE and higher leakage results.  But you cannot extrapolate forward or backward between DCA55 and DCA75 hfe or leakage results.  It depends on the range of HFE and leakage of the transistor under test, transistor model, etc.  With the DCA75, you can change the test parameters and graph the results, which is cool.  But you have to be hooked to a PC and take the extra time.  Maybe not what you want to do when you are grading a batch of transistors or trying to pick some for a build. 

I bought a DCA75, not realizing that.  I had problems when I would buy graded transistors, and when I was doing builds.  Once I figured out what was going on, I switched to a DCA55 and things are better now.  Of course neither are measuring at the circuit levels, but then the methods used to devise the rules of thumb we have probably don't either.  It's all just guidelines to get you in the ballpark.  But the DCA75 results are less compatible.

I contacted Peak Atlas about this oddity that their meters give different answers, by design.  Also made several suggestions on how to easily make the DCA75 more compatible.  They were polite, perhaps interested, but that was months ago and I haven't heard from them again.

I use my DCA all the time for diodes and transistors.  Never have to look up or remember pinouts!

I use an LCR meter for measuring resistors and caps, not my DCA.

[oip]

got something very similar off ebay a few weeks ago



as others have said, it's pretty funky with gain readouts, seems ballpark only and mine displays substantially lower than other methods.  but so far has been extremely handy to have sitting around for pinouts and identifying random components.

personally i got the kit version but wouldn't recommend this, it was mildly annoying to build (solder rings through the PCB are very thin) and in retrospect not really worth saving a few bucks.


great info about the peak testers will look into the DCA55

[lars]

I thought this device looks very interesting; it can test and identify IC's as well as transistors, diodes, etc, (not sure if it tests caps). This would be very helpful especially in cases of IC's where the identifying marks are sanded off, or have obscure in-house numbers. It can be had off Ebay for about $30.