Search found 17973 matches

by Mike H
Tue Feb 19, 2019 7:03 pm
Forum: Valves
Topic: For high-power enthusiasts
Replies: 5
Views: 94

Re: For high-power enthusiasts

Note the warnings about radiation hazard. :D
by Mike H
Mon Feb 18, 2019 2:18 pm
Forum: Everyones Projects
Topic: remote hv power supply
Replies: 3
Views: 60

Re: remote hv power supply

I use Mate-N-Lok. Available from Mouser, RS, Rapid, eBay, Vehicle Wiring Products, do a Google search. 600V and several Amps - can't remember exactly what - but means I can use them for heater supplies as well. 1-way to 15-way, male & female. Female (I think) can be pressed into a rectangular hole i...
by Mike H
Mon Feb 18, 2019 2:01 pm
Forum: Jokes
Topic: A little light humour
Replies: 1598
Views: 206356

Re: A little light humour

Tidying up my "\Temp" folder, found this again. Taken from a Moto Guzzi motorbike forum - I once spent several hours looking at a Honda that refused to start. It was a favour to settle a family argument. Father and son were not speaking. Father was a Senior engineer for a high tech engine company. S...
by Mike H
Mon Feb 18, 2019 1:58 pm
Forum: Jokes
Topic: A little light humour
Replies: 1598
Views: 206356

Re: A little light humour

Yes some people are really struggling to find something to do :lol:
by Mike H
Sun Feb 17, 2019 9:16 pm
Forum: Jokes
Topic: A little light humour
Replies: 1598
Views: 206356

Re: A little light humour

Floppy disc drives play Star Wars

by Mike H
Sun Feb 17, 2019 5:42 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

That would be a great help then. (gapped cores.) :D
by Mike H
Sun Feb 17, 2019 5:36 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

Watch out for imbalanced anode currents, If the two valves are not an exactly matched pair. DC offset will reduce transformer inductance. Unless the transformers have gapped cores. Ideally needs presets to indiviually adjust grid bias and equalise the anode currents. I had this aggro with a GEC Will...
by Mike H
Fri Feb 15, 2019 8:31 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

RhythMick wrote:
Fri Feb 15, 2019 4:18 pm
I haven't seen any recent opinions on 2.
OK, yeah! Filament goes t!ts up, other valve is saved. Hoorah! All gorn quiet, = alerts user that summat's up. Nowt ambiguous about that. :D
by Mike H
Fri Feb 15, 2019 3:36 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

So if supply is 8V, then in my last diagram:

R4 = 680R
R2 = 7.5k

Proper job. :D
by Mike H
Fri Feb 15, 2019 3:32 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

Getting very complicated again. Batteries? Nah. :D I like this: Something like this ? 1550185320490414.jpg Comparator circuit current is VERY small so I can't see a problem with supply "loading". The biggest current will be the LED, and only when it's on. KISS (Keep It Simple Sweetums :D )
by Mike H
Thu Feb 14, 2019 9:54 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

It does. Thanks. Would work for the 71A and 45, not for the 26. Clever though. I see what you mean. (Had to go look at 26 data.) I don't know what the heater PSU circuit looks like, but would hazard a guess there is a higher Voltage available from there (e.g., before regulator), that could power th...
by Mike H
Thu Feb 14, 2019 6:01 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

PS: you will only be able to use one comparator in the chip, because the heater supplies are separate circuits, so you can't share two halves of the chip between both valves. Hope that makes sense.
by Mike H
Thu Feb 14, 2019 5:57 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

OK second attempt - hopefully this is easier to understand - but all I've done is change values for a 2.5V supply. The crucial thing is tho, it is powered by the 45 heater supply module, so is very simple to do. No separate supply is necessary! :D
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Heater LED Warning-2.jpg
by Mike H
Thu Feb 14, 2019 5:12 pm
Forum: Everyones Projects
Topic: Warning LED when valve stops conducting - a little SS help needed
Replies: 120
Views: 1181

Re: Warning LED when valve stops conducting - a little SS help needed

How are the filaments heated? Andrew's DC boards. At present there's 1 board per valve, 12 boards total. I did consider early on using those boards to drive the valve pairs in series, which would stop current if either fails (with series heaters there could be no virtual cathodes). I don't know the...
by Mike H
Thu Feb 14, 2019 5:01 pm
Forum: Jokes
Topic: A little light humour
Replies: 1598
Views: 206356

Re: A little light humour

"I don't have an exact date, but it's roughly the same time that the sun becomes a cold dark chunk of coal the size of your forehead."

"We'll need flashlights."

"And sweaters. It could get nippy."