Low Cost Huntron 2000 - Circuits, Plans & Ideas!

[Chris56000]

Hi!

So as not to intermingle one thread into a confused mess, I've started this separate thread to post my design ideas, schematics and ideas to make a low cost Huntron 2000 style Component Tracker that performs equivalently to the genuine instrument, but without needing any scarce parts like the XR2209 and the uA759, can be built with low-cost standard parts and cheap Asian modules - (EPE Magazine is doing a series on these Modules), or readily available ICs still in production.

My first priority is to design a replacement for the three-frequency (50Hz, 400Hz and 2000Hz) oscillator phase-locked to an a.c. mains reference that does NOT require any end-of-life devices - altho' 8038s are considered to be E.O.L., there appear to still be plentiful stocks in China, but a discrete solution is better if I can work out one!

I consider that a substantial saving of hundreds of £ can still be made compared to the silly prices Sellers are asking for these instruments!

Chris Williams

[trigskraj]

Look
adrupus  -- https://www.excelworks.info/Arduino.html
analog signature -- http://analogsignature2.wixsite.com/analog

[fastguido]

Why do you think that Huntron needed the oscillator to be phase locked to the AC mains ? I appears that they only phased locked the 50/60 hz frequencies, not the others. If what I am seeing the reference just auto selects which freq. to use 50Hz or 60Hz.

[schmitt trigger]

I was shown Huntron tracker back in the early 90s in a visit to an military electronics assembly house. The technicians loved it, they would  fully troubleshoot complex assemblies utilizing only this instrument and a golden unit.

I became hooked too, and purchased several for my technicians where I used to work.

Then if I recall properly, Tektronix purchased Huntron, and made a fancy, Tektronix-priced unit. Apparently they sold poorly and were discontinued.

Thus, original Huntron units command very high prices.

But back to the topic at hand; Of course either 50 or 60 Hz were derived from the power line. But 400 and 2000 Hz were internally generated and were not exceptionally precise, +/-3% if I recall properly, on a new unit. And they didn't need to be accurate anyways.

Nowadays, these frequencies would be easily synthesized with a microcontroller.
But hey!, some of us like analog oscillators. The choice is yours.

[kripton2035]

you could also do this freq generator ( and the rest of the device) using some cypres psoc. you have everything you need analog+digital inside.

[kripton2035]

adrupus  -- https://www.excelworks.info/Arduino.html

seems to be everything the OP needs.

[Chris56000]

Hi!

Oh dear, my friend's just bought a 6L01i miniature Russian CRT and two cheapie H.T Generstor  Chinese "cheap as chips," modules of the sort reviewed in EPE Magazine now!

I have to confess my friend's not over–pleased with trying to compile and build projects from other chaps' source–code & sketches as we can never get 'em to work as described by the project author!

It's for this reason I didn't want to go down the Cypress/ARM/PIC/Arduino route as we're not software skilled I'm afraid – I'll make anything of any complexity using discrete components and simple chips, but I want to make sure nothing's getting scarce first – "Littlethief" as a few of my work colleagues unkindly christen 'em, want £124.90 for an XR2209 VCO chip when I looked fairly recently!

Chris Williams

[wardie]

 The work has been done for you.
 If you have read the notes that accompany the Ardupus / Octopus project, I would
be interested to learn of any features you feel are lacking, or not well implemented.
 I would recommend (and myself use) the simplest single window, single probe version.
 These hand held designs are far more useful than a Huntron for most of us.
Peter

[Chris56000]

Hi!

The reason why myself, my friend Steve & several work colleagues prefer the Huntron's principle, rather than the Arduino–based designs, is that we have come across many suspect devices that would simply pass as perfect on an Arduino based tester, show up defects when tested on the "Hi" range (60Vpk) of my employer's instrument, our experience has proved over many years that cheapie low–voltage only test circuits miss out marginal components that can cause the most obscure symptoms!

Therefore, the "Ardupus" designs do not meet my requirements as defined by many years of fault–location experience, both at home on my personal gear and in my employment!

An Arduino "Nano" or similar, suitably programmed, could read the control–buttons and operate the function–indication LEDs, etc, but I would still require the remainder of the analog circuitry in order to provide an adequate test voltage, up to 60V rms at 25mA at the three test frequencies!

Chris Williams

[wardie]

 Thank you for stating your needs, Chris.
 Yes, if you need brute force like that, it would be difficult in a hand held. The Huntron 1005B only delivered max about 0.28 mA RMS at both 40 and 120v P/P, which is a long way short of what you ask. I see the latest Huntron now uses a max 20v.
 I plan to revisit the Ardupus, and will incorporate increased voltages and a range of frequencies. Despite being Arduino based,
the Ardupus works on exactly the same principle as the Huntron.
 As the essence of comparison is the ability to differentiate, trace comparison in the next versions will be enhanced by mathematical comparison of averaged traces (area within a loop, etc), and perhaps a move to 16 bit.
By making comparisons using trace data (as well as the usual visual) will go a fair way to  compensate for using a lower max voltage.
I speculate that this is the approach allows the current Huntron to do its job with a much lower max voltage than before.
Peter

[Chris56000]

Hi!

The power supply and CRT driver circuits in my design are complete and I'm now waiting till pay–day to order the CRT, case, transformers and the voltage regulator modules I propose to use!

Can I use the transformer equation:–

Ep = 4.44 × f × B x A × Np


. . .with an Epcos N87 series transformer kit to make the signal–voltage transformer?

I presume the "area" parameter given by Epcos in their E32 series, etc., datasheets corresponds to 'A' in the basic transformer equation!

The transformer primary would be wound for 9.5V rms at 50Hz, then the primary volts needed for 400 & 2000Hz determined either from the transformer equation or by direct experiment.

Would I need to provide two primary taps, or is it simpler to adjust the oscillator voltage/power amp gain to give the same secondary outputs at 400Hz & 2000Hz?

Chris Williams

PS!

I forgot to mention – is 'A' in the transformer equation the effective c.s.a. of the core itself or the winding–space area, or the sum of both?

(It's forty years since I studied this in detail at college!)

[schmitt trigger]

I may be wrong, but those Epcos cores may not have sufficient window area to wind the required amount turns for such large applied volt-seconds.

A salvaged steel-core audio transformer, with a turns adjustment, may do the trick.

Or if you have access to high grade silicon steel, like an M6 or M5, you could design your own.

And drive it with any audio power amp IC.

[fastguido]

I am designing a DIY Huntron too , but I am starting with the guts of an old Heathkit 3" CRT vector monitor for the CRT portion( I like CRT's). I am going to use a MPU to replace the Huntron logic portion. Why can't you use an audio amp IC (i.e. LM 3875 or something similar ) with a > +/-30 volt supply to get a 60v pk-pk output instead of a transformer , it would seem that you would have voltage available since you are using a CRT with it associated power supply.

[kripton2035]

although I understand some can prefer a crt display for a component tester, I'm planning to make one with a good lcd display, to make things more modern !

[2N3055]

Audio trafo for 100V PA speaker might do the trick..

[schmitt trigger]

That is an excellent idea! a 70 volt speaker line matching transformer:

https://www.amazon.com/Parts-Express-Speaker-Matching-Transformer/dp/B0002KRA1U?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-ffnt-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B0002KRA1U

[Chris56000]

Hi!

Member Schmitt Trigger, thank you – I'd forgotten all about 70V/100V line transformers – an Eagle P037 is just about the right size and power–rating for a Huntron high–voltage project and is designed for operation at the audio frequencies used!

Also it's primary can be driven from a cheap eBay diy kit power amplifier module, leaving only the oscillator bit now!

Thank you for your input – I know about 100V p.a. working, but hadn't realised small 100V transformers less than 10W were readily available!

Chris Williams

[kripton2035]

there is a nice supply for such a tester, that goes up to 80V here :
https://www.changpuak.ch/electronics/Curve_Tracer_advanced.php

[vk6zgo]

At my old work, we had a Huntron 2000, which spent most of it's time unused.
Only one bloke seemed to have success with it, & swore by it---- the rest of us swore at it!

I tried it once, comparing between a good & bad board, with no satisfaction.
My feeling was that if you had a spare good unit, you could compare normal operating voltages, waveforms, etc easier.
I could see that if you were testing a lot of identical boards, it could work for checking them against a good board, without needing to fire the complete device up, but that was rarely the case with our work.

[schmitt trigger]

The Huntron Tracker is like Vegemite. Definitively an acquired taste.

For the record, I love both the Tracker and Vegemite.
Vegemite and avocado......delicious.