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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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16th Dec 2017, 1:41 pm | #1 |
Hexode
Join Date: Feb 2014
Location: Southampton, Hampshire, UK.
Posts: 419
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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 |
16th Dec 2017, 4:36 pm | #2 |
Guest
Posts: n/a
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Re: Triode curve tracer
Looks promising, maybe add series resistors from the (expensive) DAC too.
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17th Dec 2017, 7:36 am | #3 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,667
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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.
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17th Dec 2017, 9:22 am | #4 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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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.
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20th Dec 2017, 1:28 pm | #5 |
Hexode
Join Date: Feb 2014
Location: Southampton, Hampshire, UK.
Posts: 419
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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 |