Which options do I have for passive components testing - Cheaper alternatives?

[petemate]

Hi guys,

I'm looking to add an instrument that will be able to do passive component testing. From work I have experiences with e.g. HP 4194A, PSM1735 and Bode 100, which are all frequency response analyzers and/or impedance analyzers. I'm a big fan of the Bode 100, but they are expensive and hard to come by. What options do I have for a more reasonably priced solution? I don't want one of the fixed-frequency (handheld) LCR meters. I want something which is able to characterize components from almost-DC to at least a few megahertz. Basically I want something as close as possible to the units mentioned before, but without paying as much What are my options? I'm fine with DIY and kits, by the way.

[egonotto]

Hello,

perhaps you should look at the Analog Discovery. In my opinion a very good solution.

You can also look at Red Pitaya and Picoscope with FRA (https://www.picotech.com/library/picoapp/frequency-response-analyzer-with-bode-plots)

Best regards
egonotto

[petemate]

Hi, thanks for your answer! I had a look at the Red Pitaya, but you gotta go to the largest package in order to get the LCR meter version. And it only does discrete steps up to 100 kHz. The analog discovery seems cool, though. I'm just concerned that it won't be more than a novelty item.

Maybe I should just build my own. A scope, a function generator and some software should be enough for most jobs.

[DaJMasta]

Your best options are pricey... usually either a low frequency VNA with impedance measurement options or an impedance analyzer that would similarly break the bank.  If you don't mind a little slower sweep, though, you could get an older LCR meter or impedance analyzer (Hioki bench LCRs can be a few hundred bucks, sometimes a Wayne Kerr, then older HP LCRs or boat anchor impedance analyzers), then script out a sweep of frequencies over GPIB.  Not going to be nearly as fast as a unit designed for sweeping, but you could get the data you are looking for, at least.

Perhaps one of the LCR meters designed for high speed verification testing could make for faster sweeps when controlled for that.

[SilverSolder]

The HP 3575A is a "relatively compact boat anchor", beautifully made, that will do 1Hz - 13Mhz according to the specs and they go for real cheap on eBay.

You drive it with your existing signal generator and it displays the gain and phase between its two ports.  You can get the data out the back of it through an analog voltage that you can log on a scope for Bode plots etc.

It is definitely able to characterise components like resistors, electrolytics, inductors, etc. as long as you don't need sub-PPM results...  think 1970's Pontiac GTO with a 455 with functional ram air intakes on the hood, rather than a Porsche, Audi, or BMW, and you get the idea!

[Kean]

If you're willing to do some DIY, a low cost option is the Arachnid Labs Tsunami
https://www.crowdsupply.com/arachnid-labs/tsunami

It isn't available any more for purchase, but it is completely open source.
https://github.com/arachnidlabs/tsunami
https://github.com/arachnidlabs/tsunami-arduino

I've used it to do frequency plots on various components including ultrasonic transducers, but only ever up to about 100kHz.

[David Hess]

Cleverscope makes some USB DSOs which support low frequency network analysis which will do exactly what you want but they are not cheap.  Syscomp Electronic Design has some as well.

[cdev]

Sounds like something that a Bitscope might be able to do?

[Doctorandus_P]

This looks very much like what you want. It is definately on the hobby level, but also for hobby prices. The results look much better than what you'd expect from a hobby level product though:

The Hardware
The hardware for the Simple Scalar Network Analyser (SSNA) consists of a host PC which provides the user interface and a USB connected signal generator/power detector module.

The signal generator is an inexpensive AD9850 DDS module which can be bought on Ebay or from a number of electronics suppliers for about $10 USD. The AD9850 chip can synthesize a fairly clean sinewave  and in this application the useful range is about 1MHz to 30MHz.

The power detector uses an Analog Devices AD8307 log power detector chip. The AD8307 has a range of  -75dbm to +17dbm from DC to 500MHz. A $3 Arduino Nano clone controls the DDS and digitizes the analog output of the AD8307. The Nano has a built in USB to serial interface which is used to communicate with the host PC. The signal generator/power detector module runs off 5V USB power and consumes only 150ma from the host PC, which

http://rheslip.blogspot.com/2015/08/the-simple-scalar-network-analyzer.html

Now I'm wondering....
What would be needed to add phase response measurements to this device?

When the output of both the AD9850 and the AD8307 are cleaned up a bit (comparator, / 74hcu04) and combined with an edge triggered S/R flipflop  put through a low pass filter you have a low frequency signal which changes with phase and can be easily measured with a uC.
Would a chip like the BUF634 be an improvement for the output amplifier/buffer?

I'm not sure how usefull it is to add this. Any opinions?

[petemate]

This looks very much like what you want. It is definately on the hobby level, but also for hobby prices. The results look much better than what you'd expect from a hobby level product though:

The Hardware
The hardware for the Simple Scalar Network Analyser (SSNA) consists of a host PC which provides the user interface and a USB connected signal generator/power detector module.

The signal generator is an inexpensive AD9850 DDS module which can be bought on Ebay or from a number of electronics suppliers for about $10 USD. The AD9850 chip can synthesize a fairly clean sinewave  and in this application the useful range is about 1MHz to 30MHz.

The power detector uses an Analog Devices AD8307 log power detector chip. The AD8307 has a range of  -75dbm to +17dbm from DC to 500MHz. A $3 Arduino Nano clone controls the DDS and digitizes the analog output of the AD8307. The Nano has a built in USB to serial interface which is used to communicate with the host PC. The signal generator/power detector module runs off 5V USB power and consumes only 150ma from the host PC, which

http://rheslip.blogspot.com/2015/08/the-simple-scalar-network-analyzer.html

Now I'm wondering....
What would be needed to add phase response measurements to this device?

When the output of both the AD9850 and the AD8307 are cleaned up a bit (comparator, / 74hcu04) and combined with an edge triggered S/R flipflop  put through a low pass filter you have a low frequency signal which changes with phase and can be easily measured with a uC.
Would a chip like the BUF634 be an improvement for the output amplifier/buffer?

I'm not sure how usefull it is to add this. Any opinions?

Very interesting project! More on a hobby level, but still useful(especially for the price). I actually think I do have some of these parts, so it shouldn't be too hard to knock out in a weekend or so.

Adding phase detection would in theory be possible if you could get a hold on the phase between the different signals. You could use something like an AD0302 module to do this, although it is limited to a minimum frequency of 1Mhz.

[Gerhard_H]

Hi,
I am really happy with my VNWA from SDR kits. It runs from 1kHz to 1.3GHz. With slightly reduced performance it can even start at 200Hz.
It does not only impedance measurements but also transfer measurements and time domain measurements.
Attached is the measured resistive and reactive impedance of a PFC coil I did yesterday to check out the two port shunt impedance measurement method.
I was inspired by the discussion in https://www.eevblog.com/forum/testgear/measuring-low-impedances-with-a-vna/
The price of the VNWA is in the same range as the Red Pitaya, which I use as a HF HAM transceiver.