The Mongrel

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Re: The Mongrel

Postby Steve Anderson » Wed Sep 15, 2021 4:04 pm

Not really 'off topic' as you're using tubes/valves anyway.

I agree with all the author puts forward. I have a valve/tube mic pre-amp I built for when I'm using Skype or similar...for no particular reason, I just fancied doing it!

Very simple, an EF86 in triode mode plus a 9002 tube as a cathode follower. The heater for the EF86 is fed from DC to reduce hum, but the EF86 is well screened internally, so one could say it's not really necessary, but again, it's a whim.

Originally the EF86 was in the conventional pentode mode, but it had too much gain, around 44db (x160-ish), now it's 28db (x25). That's one of the trade-offs with triodes, lower gain, but that's what I needed. Schematic below, the original pentode version, I haven't created the triode version (yet). I may have posted this before...

EF86 Mic Preamp III.gif


Steve A.

Here's the silicon version it replaced...the LM394 is a matched super-beta low noise transistor pair, now made of Unobtainium...I did also do a lower gain version..

LM394 Mic Preamp 1.gif


LM394.pdf
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Re: The Mongrel

Postby Harry Dalek » Wed Sep 15, 2021 5:25 pm

Steve Anderson wrote:Not really 'off topic' as you're using tubes/valves anyway.

I agree with all the author puts forward. I have a valve/tube mic pre-amp I built for when I'm using Skype or similar...for no particular reason, I just fancied doing it!

Very simple, an EF86 in triode mode plus a 9002 tube as a cathode follower. The heater for the EF86 is fed from DC to reduce hum, but the EF86 is well screened internally, so one could say it's not really necessary, but again, it's a whim.

Originally the EF86 was in the conventional pentode mode, but it had too much gain, around 44db (x160-ish), now it's 28db (x25). That's one of the trade-offs with triodes, lower gain, but that's what I needed. Schematic below, the original pentode version, I haven't created the triode version (yet). I may have posted this before...

The attachment EF86 Mic Preamp III.gif is no longer available


Steve A.


Here's the silicon version it replaced...the LM394 is a matched super-beta low noise transistor pair, now made of Unobtainium...I did also do a lower gain version..

The attachment EF86 Mic Preamp III.gif is no longer available


The attachment EF86 Mic Preamp III.gif is no longer available
[/quote]

Going off track Steve as in thinking about a future try with some small Russian valves i got on site below 6J1B-V to play with in the future but they are all pentodes and i was looking into if i needed a triode i could adjust these when needed .could buy a few dual triodes i suppose but they are a bit more pricy if you call 3 dollars pricy :lol:
86efcfbd6f1c.jpg
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https://tubes-store.com/product_info.ph ... ts_id=1235
Arrrr Unobtainium ! now thats hard to get :lol:
I like your preamp went from the transistor ,ic type to Valve evolved in a direction as every one seems to prefer the valves amplifiers ,i don't think you post this before new to me .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The Mongrel

Postby Steve Anderson » Wed Sep 15, 2021 6:04 pm

Harry Dalek wrote:I like your preamp went from the transistor ,ic type to Valve evolved in a direction as every one seems to prefer the valves amplifiers..

I don't want to open 'a can of worms' here, but there's no magic, no mystique, or anything objectively 'better' with valves/tubes. They obey the laws of physics as everyone and everything does. Sorry to any valve/tube audiophiles here. I like valves/tubes simply as they are a link to my past, and a link to our collective past. Nothing more. There are applications where tubes/valves are still better suited, but as time goes on they are becoming less and less.

So really, in the context we're dealing with here (not audio, despite my earlier posting) there are applications where vacuum-state electronics still are applicable. Here it's primarily interfacing with electrostatic CRTs, though there are now plenty of semi's capable of doing the same job.

As before, it's whim, a fancy, choose your own poison...

I concede that a bunch of glowing tubes is better looking than a batch of 2N3055s bolted to a heatsink...

Steve A.
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Re: The Mongrel

Postby Harry Dalek » Wed Sep 15, 2021 9:11 pm

Steve Anderson wrote:I don't want to open 'a can of worms' here, but there's no magic, no mystique, or anything objectively 'better' with valves/tubes. They obey the laws of physics as everyone and everything does. Sorry to any valve/tube audiophiles here. I like valves/tubes simply as they are a link to my past, and a link to our collective past. Nothing more. There are applications where tubes/valves are still better suited, but as time goes on they are becoming less and less.


I just look at it its how it was done with no other choice at the time but like every thing you to look back fondly to things that existed in your earlier life ....except school !

So really, in the context we're dealing with here (not audio, despite my earlier posting) there are applications where vacuum-state electronics still are applicable. Here it's primarily interfacing with electrostatic CRTs, though there are now plenty of semi's capable of doing the same job.

As before, it's whim, a fancy, choose your own poison...


True lot of different ways using electronics of different eras to get the same results ,its nice but to give it a go hands on ,i do favor earlier eras i know every thing gets bigger but perhaps not better ...

I concede that a bunch of glowing tubes is better looking than a batch of 2N3055s bolted to a heatsink...

Steve A.
[/quote]

Funny enough i came across a video where the subminiature vacuum tubes are horivontal and on a heat sink a amp again i think ..Yes teh glowing tubes any type are very pleasing to look at .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The Mongrel

Postby Harry Dalek » Sun Sep 19, 2021 9:48 pm

I was mistaken with the results with the current sync separator and its best after a few days of testing to start again here on the sync separator side of it .
After a lot of reading i think the way forward is to use a circuit called the transitron sync separator.
It uses a EF 91 which equivalent is a 6AM6 the EF91 was replaced in mid 1950 with The EF80 so i have many of those .
What i can see the timing capacitor C1 would need to be adjusted ,looks simple enough to build ,so work on this next see how it go's .
http://www.r-type.org/articles/art-135.htm
easier to read pdf below
bestPractical-Television-1954-07-best.pdf
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The Mongrel

Postby Harry Dalek » Fri Sep 24, 2021 4:12 pm

A week of head scratching wondering why my line oscillator refuses to sync at all i worked out it was the scope probe causing the problem on the above sync separator output capacitor :roll:
It now syncs , video level control sensitive but sync it does .
My camera for some reason didn't record to the sd card so have to do that again show results .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Mongrel

Postby Harry Dalek » Fri Sep 24, 2021 7:54 pm

I am syncing the line phantastron oscillator in video below ,i seem to have to set up the oscillator each time i power on for syncing well so far just managed to get it to do that from this afternoon ,i am thinking since the circuits don't have a regulated supply voltage this must be a problem or part of it tweaking part values i will have a look at next .
Any case i can get the line to sync so a step forward and interesting learning how to use Valves again

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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Mongrel

Postby Harry Dalek » Thu Oct 14, 2021 3:31 pm

Haven't posted for a while but have been working on the monitor ,i hooked up the CRT today just to see how things would work with it .
So wired up another 3BP1 but looks like i still have to learn more about the deflection side ! i was expecting better this shameful !
I really only have one axis deflection plate working either axis at the moment still this is pretty small ~ ! only good thing so far nothing blew up ! and it seems to be behaving, not that i can see to much yet but linearity looks ok
This morning i had nothing even to power the CRT up so better than nothing another step .
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
"Fester! Don't do that to 'Thing'"
 
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