Valve curve tracer - UK Vintage Radio Repair and Restoration Discussion Forum

Ed_Dinning · 13th Jan 2010, 10:20 pm

Hi Gents, as there is a lot of interest in valve testers, try this circuit for size. A valve curve tracer from Electronic Engineering in the 50's.
Full details can be provided if any one wishes to build it (and has a good stock of uniselectors)

Ed

glowinganode · 13th Jan 2010, 11:08 pm

Interesting design, any chance of some more detail on the power supply section? I assume this unit was used with a CRO.
Thanks, Rob.

Skywave · 14th Jan 2010, 1:33 am

A thought . . .

At a glance, most of the (highly complicated-looking) switchery seems to perform 'selection' functions. Therefore, I wonder if some brave soul would care to undertake a modern version, using logic gates (data selectors, multiplexers, etc.) for this part of it and the necessary TTL to HV level translation interfaces?

Al. / Skywave.

julie_m · 14th Jan 2010, 6:24 pm

This is almost a candidate for building a computerised version.

You'd need a D-to-A converter and some op-amp signal conditioning to apply a variable negative voltage to the grid, some relays as a "high-voltage D-A converter" to apply a voltage to the anode (or would this be do-able with semiconductors?), and an isolation amplifier and A-to-D converter to measure the anode current.

It's a real shame the old ISA bus went extinct, because it was so easy to interface to. (Part of me thinks that was a factor in its demise, can't have plebs making stuff that plugs into a PC, oh no.)

brianc · 14th Jan 2010, 8:35 pm

The switch labelled "Selector Unit" is a uniselector is it not? It must make a real row when it motors. The lever-key switch to the left of the selector looks as though it will step it or in the other position it brings in a relay "oscillator" which will cause the selector to motor! As is said in earlier posts, a real candidate for logic-izing!
Cheers
Brian

Ed_Dinning · 14th Jan 2010, 9:25 pm

Hi Gents, I'll try to get some scans of the full system to post. It is from the Aug 1956 edition of Electronic Engineering and runs to several pages. The author was from min of transport and civil aviation.
A CRT unit (possibly ex-radar) was used for the display. Various uniselectors to step the voltages to the electrodes.
There were several good articles on valve technology in these magazines over the years, does anyone else have copies?

Ed

Ed_Dinning · 15th Jan 2010, 10:08 pm

Hi Gents, attached the full article for any brave soul to attempt (I may even have some spare uniselectors!

Ed

13th Jan 2010, 11:08 pm	#2
glowinganode Octode Join Date: Apr 2009 Location: Aylesbury, Buckinghamshire, UK. Posts: 1,522	Re: Valve curve tracer Interesting design, any chance of some more detail on the power supply section? I assume this unit was used with a CRO. Thanks, Rob. __________________ We have done so much, for so long, with so little, we are now qualified to do anything with nothing.

14th Jan 2010, 1:33 am	#3
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Valve curve tracer A thought . . . At a glance, most of the (highly complicated-looking) switchery seems to perform 'selection' functions. Therefore, I wonder if some brave soul would care to undertake a modern version, using logic gates (data selectors, multiplexers, etc.) for this part of it and the necessary TTL to HV level translation interfaces? Al. / Skywave.

14th Jan 2010, 6:24 pm	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Valve curve tracer This is almost a candidate for building a computerised version. You'd need a D-to-A converter and some op-amp signal conditioning to apply a variable negative voltage to the grid, some relays as a "high-voltage D-A converter" to apply a voltage to the anode (or would this be do-able with semiconductors?), and an isolation amplifier and A-to-D converter to measure the anode current. It's a real shame the old ISA bus went extinct, because it was so easy to interface to. (Part of me thinks that was a factor in its demise, can't have plebs making stuff that plugs into a PC, oh no.) __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

14th Jan 2010, 8:35 pm	#5
brianc Rest in Peace Join Date: Jun 2004 Location: Burghfield, Reading, Berkshire, UK, Posts: 1,055	Re: Valve curve tracer The switch labelled "Selector Unit" is a uniselector is it not? It must make a real row when it motors. The lever-key switch to the left of the selector looks as though it will step it or in the other position it brings in a relay "oscillator" which will cause the selector to motor! As is said in earlier posts, a real candidate for logic-izing! Cheers Brian

14th Jan 2010, 9:25 pm	#6
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Valve curve tracer Hi Gents, I'll try to get some scans of the full system to post. It is from the Aug 1956 edition of Electronic Engineering and runs to several pages. The author was from min of transport and civil aviation. A CRT unit (possibly ex-radar) was used for the display. Various uniselectors to step the voltages to the electrodes. There were several good articles on valve technology in these magazines over the years, does anyone else have copies? Ed