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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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8th Jan 2024, 10:17 am | #21 |
Nonode
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,085
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Re: ECC81 with broken glass envelope meets 2 x LND150 transistors
Thanks for the discussion: there was a lead time of many months for the LND150 transistors to arrive at the local RS, and then I started looking for the 'circuit', which is defined only as above, and would mean N-chan MOSFETs being reverse pol'd. Further, the photo of the device being tested seems to show the devices with the round side facing out through the envelope, and the pin connections are indiscernible.
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11th Jan 2024, 1:42 pm | #22 | |
Hexode
Join Date: Mar 2019
Location: Edinburgh, Scotland, UK.
Posts: 341
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Re: ECC81 with broken glass envelope meets 2 x LND150 transistors
Quote:
It didn't work! - complete silence. I then tried them facing in and all is good, they survived the test and sounded good. Doug. Last edited by dougietamson; 11th Jan 2024 at 1:44 pm. Reason: attache photo |
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11th Jan 2024, 3:12 pm | #23 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: ECC81 with broken glass envelope meets 2 x LND150 transistors
If they are MOSFETs or DMOS, then there will be a back gate tied to probably the source pin. This will definitely make them asymmetric.
Some JFETs are symmetric and can be used either way. Some transceiver designs used this in bilateral amplifiers where by swapping the bias supply for the drain from one end to the other, the amplifier would reverse and amplify in the opposite direction! David
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11th Jan 2024, 5:00 pm | #24 |
Nonode
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,085
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Re: ECC81 with broken glass envelope meets 2 x LND150 transistors
Thanks Doug - very interesting! They are indeed DMOS, and N-channel depletion mode, so Source to Cathode, Drain to Anode!
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- Julian It's good here Last edited by Julesomega; 11th Jan 2024 at 5:06 pm. |