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

G4_Pete · 16th Dec 2017, 1:41 pm

Hi, I was just wondering if with sutable buffering if a Peak Atlas component tester could analyse a triode. Lots of other ways to achive without zapping a Peak Atlas analyser I know, but just a thought.
Overview attached.
Pete

16th Dec 2017, 4:36 pm

Looks promising, maybe add series resistors from the (expensive) DAC too.

Diabolical Artificer · 17th Dec 2017, 7:36 am

Interesting idea, how would you make the buffers? There's a high voltage opamp - LTC6090 made by Linear that may do the job.

Andy.

julie_m · 17th Dec 2017, 9:22 am

As part of the process of designing homebrew amplifier, I needed some plots of cathode current against grid and anode voltages. I used the ADCs and one DAC of a Velleman K8055 interface board, with a dual op-amp to level-shift the grid voltage (I didn't need to go below -9V) and amplify the voltage developed across a 10Ω resistor in the cathode, with just a simple potential divider to get the anode voltage.

The worst bit really was getting power into the whole arrangement .....

Were I doing it all over again, I think I'd use a HCPL7800 or similar to measure the current through a sense resistor in the anode, so the arrangement could be extended to tetrodes and above without G2 current affecting the readings; and connect a couple of relays to the digital outputs, to switch the HT and heater supplies.

G4_Pete · 20th Dec 2017, 1:28 pm

By coincidence the November 2017 VMARS "Signal" journal dropped through the letter box today with an article on a microprocessor controlled valve curve tracer.

Pete

16th Dec 2017, 1:41 pm	#1
G4_Pete Hexode Join Date: Feb 2014 Location: Southampton, Hampshire, UK. Posts: 419	Triode curve tracer Hi, I was just wondering if with sutable buffering if a Peak Atlas component tester could analyse a triode. Lots of other ways to achive without zapping a Peak Atlas analyser I know, but just a thought. Overview attached. Pete Attached Thumbnails

16th Dec 2017, 4:36 pm	#2
Guest Guest Posts: n/a	Re: Triode curve tracer Looks promising, maybe add series resistors from the (expensive) DAC too.

17th Dec 2017, 7:36 am	#3
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,662	Re: Triode curve tracer Interesting idea, how would you make the buffers? There's a high voltage opamp - LTC6090 made by Linear that may do the job. Andy. __________________ Curiosity hasn't killed this cat...so far.

17th Dec 2017, 9:22 am	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Triode curve tracer As part of the process of designing homebrew amplifier, I needed some plots of cathode current against grid and anode voltages. I used the ADCs and one DAC of a Velleman K8055 interface board, with a dual op-amp to level-shift the grid voltage (I didn't need to go below -9V) and amplify the voltage developed across a 10Ω resistor in the cathode, with just a simple potential divider to get the anode voltage. The worst bit really was getting power into the whole arrangement ..... Were I doing it all over again, I think I'd use a HCPL7800 or similar to measure the current through a sense resistor in the anode, so the arrangement could be extended to tetrodes and above without G2 current affecting the readings; and connect a couple of relays to the digital outputs, to switch the HT and heater supplies. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

20th Dec 2017, 1:28 pm	#5
G4_Pete Hexode Join Date: Feb 2014 Location: Southampton, Hampshire, UK. Posts: 419	Re: Triode curve tracer By coincidence the November 2017 VMARS "Signal" journal dropped through the letter box today with an article on a microprocessor controlled valve curve tracer. Pete