(Now a bi-weekly program)
May 7, 2013
Join the "CWTD Yahoo Group" for email discussion in between our bi-weekly sessions.
Component Testing: "A (meter's) got to know his limitations" ... Dirty Harry, circa 1971
Cool Product of the Month: The Versatile Component Tester
Sure, everyone these days knows what to measure with a DVM or even with one of the fancy, all-in-one component testers like the ubiquitous (and very good) L/C Meter II-B from AADE. But what do those measurements mean? What are the circuit implications? At what frequency does the measurement have significance for you? And what about the not-so-common measurements that can be all-important to some homebrewers ... like effective series resistance of a capacitor you dig up at the bottom of your boatanchor junk box?
Well, this time we explore these questions, and many other dimensions of measuring resistance, capacitance, inductance, transformers, transistors, ... And perhaps you'll come away from this episode with some new insights for just what components you do have in your junk box!
Oh ... and our Cool Product of the Month this time fits right in with this component test theme. We delve into the increasingly popular (and inexpensive!) component tester kit called "AVR-Transistor Tester", by Karl Kubbler and Markus Frejek, We'll show you how we added a little CWTD packaging mojo and dubbed it the Versatile Component Tester ... that you can easily replicate!
73, George N2APB & Joe N2CX
Log of Text Discussion During the Show ...
<19:57:26> "George - N2APB": Our whiteboard this evening is at http://cwtd.org/May7.html
<20:03:54> "Rick K3IND": New URL is a great idea!
<20:05:18> "Laz K2LAZ": My client panel disappeared so I could not mute it.
<20:05:48> "Ted WA3AER": RSS!! Is there, perhaps, already a CWTD feed on Twitter?
<20:12:16> "George - N2APB": Working on providing the CWTD podcasts via RSS feeds. Not there yet, but coming.
<20:15:27> "W2AEW - Alan": High ESR is a very common failure mode for cheap electrolytics in high-volume electronics, particularly switching power supplies in things like CCFL Inverter supplies in LCD monitors, etc.
<20:18:26> "Rick K3IND": Can a dried-out cap in a boat anchor actually explode?
<20:21:16> "W2AEW - Alan": Rick - it depends. if there is enough ripple current to cause significant heating, the pressure can cause an exciting failure.
<20:21:30> "Clint-ka7oei": Yes - anywhere from popping out the rubber vent to spraying metal confetti inside the chassis. Usually, they just sit there and do nothing - not even playing capacitor...
<20:22:34> "W2AEW - Alan": Here's a video I did on self-resonance of Ls and Cs: http://www.youtube.com/watch?v=vi24SpKYYoQ
<20:25:16> "George - N2APB": Alan, I just embedded your three "component measurement" videos from YouTube ... People will have to "refresh" the browswer to see the latest page.
<20:26:35> "W2AEW - Alan": Thanks George. I just put a link to a video on self-resonance in the chat window too.
<20:32:37> "Rick K3IND": Tell FET's from transistors?
<20:38:09> "W2AEW - Alan": Here is a nice blog posting regarding the measurement of Diode Capacitance and Reverse Recovery Time - so you can potentially ID/match unknown devices: http://www.scopejunction.com/author.asp?section_id=1788&doc_id=263021&
<20:39:08> "Todd K7TFC": I just logged in. Where are we on the whiteboard?
<20:39:35> "Frank N3PUU": Up to "Quartz xtals/ceramic resonators"
<20:39:43> "Todd K7TFC": Thanks!
<20:40:04> "Charles WC5MC": I bought all the components to home brew Chris Trask's Crystal Test Set. I just haven't gotten to doing a build of it yet. http://www.home.earthlink.net/~christrask/Crystal%20Test%20Set.pdf
<20:45:14> "W2AEW - Alan": I love my AADE L/C Meter - great tool!
<20:46:02> "George - N2APB": Me too. And you'll love the Versatile Component Tester too. Even if just for its ESR measurement capability.
<20:46:09> "Todd K7TFC": Chinese bare-bones testers on eBay? I have three. They compare well with more expensive units.
<20:47:38> "Clint-ka7oei": GWEN?
<20:48:54> "Rick K3IND": Dont forget ARRL Handbook has good info on building your own test instruments.
<20:49:54> "George - N2APB": GWEN = Ground Wave Emergency Network ... Joe's got lots of experience with these. http://en.wikipedia.org/wiki/AN/URC-117_Ground_Wave_Emergency_Network
<20:55:20> "Clint-ka7oei": I used to dodge GWEN in the 80's when I was heavily into the LowFER stuff - particularly the Ft. Huachuca node!
<20:57:33> "Joe N2CX": Clint, I'll be you had to dodge the GWEN stations. The 150-175 kHz operating range indeed overlapped the 160-190 kHz range that LOWFER's used.
<20:59:00> "Clint-ka7oei": My freq. was 177.750000 kHz - usually nailed down by a TCXO, often running 10 baud and 1 baud BPSK-ASCII, long before PSK31!
<20:59:43> "Terry WB4JFI": $27 with shipping an hour ago
<21:00:44> "Todd K7TFC": Mine are from Lemonbleue. Very fast delivery.
<21:04:29> "Todd K7TFC": Very nice. The SIP sockets for the DUTs on the bare board are too small and won't take thicker leads. The bananna jack/binding posts on your VCT are an excellent touch!
<21:11:46> "Todd K7TFC": One could also use any clean-edge tape to lay-out the copper gaps on the adaptors and then etch like a pcb board.
<21:15:42> "Ted WA3AER": Just ordered the tester. Something I have needed for quite a while here. TNX for the lead!!
<21:17:06> "Todd K7TFC": What's the sleep current?
<21:18:35> "Ted WA3AER": 20nA
<21:18:42> "George - N2APB": The manual says nano amps while sleeping!
<21:18:58> "Ted WA3AER": operating current = 25mA
<21:19:48> "Howie K3HW": What about Superposition, Thevenin/Norton analysis?
<21:20:19> "W2AEW - Alan": Thevenin and Norton is a good analysis technique - but generally not something applied in actual measurements
<21:20:45> "W2AEW - Alan": Superposition too - good for analysis, but not for measurements
<21:21:19> "Howie K3HW": QSL Alan
<21:21:59> "W2AEW - Alan": These techniques involve shorting voltage sources and opening current sources - easy when calculating things, but not easy in actual testing
<21:24:08> "Howie K3HW": understood Alan - remembering my college days in AC theory class
<21:24:25> "Howie K3HW": DC too
<21:24:58> "W2AEW - Alan": Good example of practical application of Thevenin and Superposition - see my video on the analysis of an R-2R resistor ladder Digital to Analog Converter: https://www.youtube.com/watch?v=AulX1OM7RwE
<21:24:59> "Todd K7TFC": Just a comment on one of the tester photos: I would not have thought the junction capacitance on an LED would be so high with forward bias.
Capacitance and other characteristics depending on construction and usage
Electrolytics and Tantalums
ESR – inducator of usefulness and useful for determining if capacitor has aged beyond utility
Table of max ESR values for electrolytic caps.
On the web at <http://www.radiodevices.info/esr/esr4_en.pdf>
Left hand vertical column is capacitance in uF
Top horizontal row is voltage rating of the capacitor.
Other values are ESR in ohms.
Usually used for audio and low RF
Measure capacitance and perhaps matching for phase shift networks and audio filters
Types of ceramic dielectrics
Used for RF, audio and power bypassing
NP0 types used for RF
So-called Hi-K dielectric types used for audio and bypassing have large variation of capacitance with
temperature – can identify these by noting that capacitance varies widely if component is exposed
to hot air gun or cold spray.
Inductors for RF
Apparent inductance varies with frequency (see powdered iron inductors)
Iron core inductors
Usually used for audio and power applications
Need to measure inductance of chokes (in Henries) and transformer primary/secondary ratio
Powdered iron inductors
Usually used for RF and power applications
Q is frequency dependent so often best to test at frequency of use
Toroid “apparent inductance” varies with placement of wire on core
Best to test at frequency of use with a Q meter
Loss varies with freq
Permeability varies with freq
Need to test at operating frequency using a Q meter
Self inductance (usually wirewound power types)
Identifying lead connections
Forward drop/matching temp variation
Identifying lead connections
Measure BE drop, beta, transconductance
ICs – specialized test equipment or custom setups
Identify turn on/off voltages and pin connections
Quartz xtals/ceramic resonators
Need special test equipment such as the K8IQY PVXO and test setups:
Appropriate test equipment
Some transistors, capacitance, inductance (rough idea, audio or power components)
Peak Component testers
analyzers for semiconductors, RLC, ESR, network cables, thyristor and triacs
Excellent dedicated purpose component test devices.
Very good handy instruments but $$ and need many to handle all component types
No control over test frequencies
AADE L/C Meter
Good very popular test device for RF type inductors and non-electrolytic capacitors
Has zeroing capabilities to null out cable and fixture stray capacitance and inductance
Long a standard on homebrewer test benches
No control over test frequencies
LCR Bridge such as the GR 1608A
Excellent commercial gear usable for a wide range of inductors, capacitors and resistors.
Manual instrument with very wide range capabilities beyond what most homebrewers need but super-cool to use!
Other commercial bridges and LCR meters exist but are beyond the budgets of all but the most ardent fan-boys.
Tunable instruments that one tunes to a desired frequency to test RF inductors and capacitors
Can test L, C and Q
Excellent instrument for the ultimate characterization of RF components
If you can find one the HP 4342A is a modern superb instrument
Vector Network Analyzer
Great for analyzing components at HF/VHF/UHF and higher – overkill for most homebrewers with a very steep learning curve
Measuring L and C with your scope: Measure Capacitors and Inductors with an Oscilloscope and some basic parts
Octopus component tester: http://www.youtube.com/watch?v=Gwo3pEH7hUE
Homemade Capacitor ESR meter: http://www.youtube.com/watch?v=bmYAgat-sOQ
Cool Product of the Month ... "AVR-Transistor Tester" ... packaged into the "Versatile Component Tester"
The AVR-Transistor Tester
Mentioned recently (April/May) on several email lists with detailed comments as “ROC” or “PROC” tester on Yahoo group qrp-tech http://groups.yahoo.com/group/qrp-tech/
Designed originally by Markus Frejek, and pimped out by Karl Kubbler with some cool software mods, this inexpensive little board does some wondrous measurements!
Vendor “lemonbleue”, Ebay item no. 330855732011 listed as”NEWEST Transistor Tester Capacitor ESR Meter Inductance Resistor NPN PNP MOSFET ... http://www.ebay.com/itm/NEWEST-Transistor-Tester-Capacitor-ESR-Meter-Inductance-Resistor-NPN-PNP-MOSFET-/330855732011?ssPageName=ADME:L:OC:US:3160
Apparently cloned by Chinese manufacturers
Manual available as “ttester.pdf” in files section of qrp-tech or HERE
Series of manuals and software for original design and upgrades can be found at: <http://www.mikrocontroller.net/articles/AVR_Transistortester>
Beware of similar items as not all of them are the latest version with resistor matching function and ESR testing ability.
Cost is under $30.00 with shipping to US
Tests resistors, capacitors above 1000 pF, inductors above 10 uH, and many semiconductors and most importantly ESR of capacitors above 10 uF.
Very handy for bench testing, matching audio and power inductors and capacitors, identifying semiconductor pinouts and characteristics. Not suitable for most RF inductors and capacitors.
1. Operates with ATmega8, ATmega168 or ATmega328 microcontrollers.
2. Displaying the results to a 2x16 character LCD-Display.
3. One key operation with automatic power shutdown.
4. Battery operation is possible since shutdown current is only about 20nA.
5. Low cost version is feasible without crystal and auto power off. With software version 1.05k
the sleep modus of the Atmega168 or ATmega328 is used to reduce current if no measurement
6. Automatic detection of NPN and PNP bipolar transistors, N- and P-Channel MOSFETs,
JFETs, diodes, double diodes, Thyristors and Triacs.
7. Automatic detection of pin layout of the detected part.
8. Measuring of current amplifcation factor and Base-Emitter threshold voltage of bipolar transistors.
9. Darlington transistors can be identifed by the threshold voltage and high current amplifcation
10. Detection of the protection diode of bipolar transistors and MOSFETs.
11. Measuring of the Gate threshold voltage and Gate capacity value of MOSFETs.
12. Up to two Resistors are measured and shown with symbols and values with up to four
decimal digits in the right dimension. All symbols are surrounded by the probe numbers of the
Tester (1-3). So Potentiometer can also be measured. If the Potentiometer is adjusted to one
of its ends, the Tester cannot di er the middle pin and the end pin.
13. Resolution of resistor measurement is now 0:1, values up to 50M are detected.
14. One capacitor can be detected and measured. It is shown with symbol and value with up
to four decimal digits in the right dimension. The value can be from 25pF (8MHz clock, 50pF
@1MHz clock) to 100mF. The resolution can be up to 1 pF (@8MHz clock].
15. For capacitors with a capacity value above 2 F the Equivalent Serial Resistance (ESR) is
measured with a resolution of 0:01
and shown with two signi cant decimal digits. This feature
is only avaiable for ATmega with at least 16K ash memory (ATmega168 or ATmega328).
16. Up to two diodes are shown with symbol or symbol in correct order. Additionally
the ux voltages are shown.
17. LED is detected as diode, the ux voltage is much higher than normal. Two-in-one LEDs are
also detected as two diodes.
18. Zener-Diodes can be detected, if reverse break down Voltage is below 4.5V. These are shown as
two diodes, you can identify this part only by the voltages. The outer probe numbers, which
surround the diode symbols, are identical in this case. You can identify the real Anode of the
diode only by the one with break down (threshold) Voltage nearby 700mV!
19. If more than 3 diode type parts are detected, the number of founded diodes is shown additionally
to the fail message. This can only happen, if Diodes are attached to all three probes and at
least one is a Z-Diode. In this case you should only connect two probes and start measurement
again, one after the other.
20. Measurement of the capacity value of a single diode in reverse direction. Bipolar Transistors
can also be analysed, if you connect the Base and only one of Collector or Emitter.
21. Only one measurement is needed to nd out the connections of a bridge rectifier.
22. Capacitors with value below 25pF are usually not detected, but can be measured together with
a parallel diode or a parallel capacitor with at least 25pF. In this case you must subtract the
capacity value of the parallel connected part.
23. For resistors below 2100
also the measurement of inductance will be done, if your ATmega
has at least 16K ash memory. The range will be from about 0:01mH to more than 20H,
but the accuracy is not good. The measurement result is only shown with a single component
24. Testing time is about two seconds, only capacity or inductance measurement can cause longer
25. Software can be configured to enable series of measurements before power will be shut down.
26. Build in self test function with optional 50Hz Frequency generator to check the accuracy of
clock frequency and wait calls (ATmega168 and ATmega328 only).
27. Selectable facility to calibrate the internal port resistance of port output and the zero o set
of capacity measurement with the self test (ATmega168 and ATmega328 only). A external
capacitor with a value between 100nF and 20 F connected to pin 1 and pin 3 is necessary to
compensate the o set voltage of the analog comparator. This can reduce measurement errors
of capacitors of up to 40 F . With the same capacitor a correction voltage to the internal
reference voltage is found to adjust the gain for ADC measuring with the internal reference.
And now the CWTD Packaging of it into the Versatile Component Tester ...
The completed packaging and the inside view
These are the tools and parts that you'll need to do the packaging
The simple "extending cables" enable us to remote the display, pushbutton and test terminals to the front panel.
The front panel overlay made by making a suitable graphic in Visio and then printing
onto a piece of 4" x 6" photographic paper. To make it extra durable you can take
the panel over to your favorite printing house (Staples, Kinko's, etc) and laminating it.
Then punch out the holes with a hand punch, or carefully cut them out with a razor blade.
Finally, attach to the front panel (which was also cut using the sample overlay template)
using double-sticky cellophane (Scotch) tape. DOWNLOAD PDF TEMPLATE
While you can use the 5-way binding posts to hold the component-under-test, a convenient adapter (or two) can be
simply fabricated to facilitate quick and easy connection of the parts being measured. Note that the copper-clad
boards have slices through the copper in two places (on bottom side too) in order to electrically separate the component
connection points from each of the 3 terminals. Also note the tinned areas when contact needs to be (reliably) made
to the binding posts (and at the SMT touch points), which will prevent copper oxidation from interfering with connections
downstream. Lastly note the three small jumpers on each adapter board that electrically connect the top-to-bottom sides.
Measurements made on a DIODE .........................INDUCTOR .............................................RESISTOR
and on a CAPACITOR ........................... And on an SMT capacitor (held with tip of pen)
Radio Shack "Project Enclosure", p/n 270-1806 ... http://www.radioshack.com/product/index.jsp?productId=2062283
Radio Shack "Multipurpose Nylon Binding Posts", p/n 274-661 ... http://www.radioshack.com/product/index.jsp?productId=2103984