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Old 11th Apr 2010, 3:15 pm   #301
Guitarist28
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Top Cap,
That looks a great piece of work there - you have made me think that I really do need fan cooling for my regulators. Is it ok to use the 12v tap off Ed's transformer?

Regards

Rob
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Old 11th Apr 2010, 4:52 pm   #302
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Rob, 12v tap on the transformer is rated to run 1A max, so you may need to be careful when testing. Max current from 6.3V and lower is 3A.
You could possibly run a 5V computer fan off the 4v tap after rectification depending on the current that is drawn.

Ed
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Old 11th Apr 2010, 6:06 pm   #303
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Ed,
Most 5v computer fans draw approx. 0.2 amps.

Regards

Rob
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Old 11th Apr 2010, 7:19 pm   #304
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Default Re: The "Sussex" Homebrew Valve Tester.

I checked the fan I have fitted, it draws 100mA at 12V and did not see that as a problem.
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Old 11th Apr 2010, 9:12 pm   #305
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Gents, fans of this sort should not give a problem running constantly as long as there are no 1/2 hour tests of valves with high current heaters.

Ed
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Old 11th Apr 2010, 10:11 pm   #306
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Default Re: The "Sussex" Homebrew Valve Tester.

I had a quick run through my valve books and most 12.6V valves have heater currents mostly of 150 to 350mA. The highest I found was a rectifier which required over 3 Amps! Must be one hell of a rectifier and would be out of range for the transformer, fan or not. I shall be using the tester for mainly small receiver types, any special ones of the P or U series will be supplied by an external supply. The transformer loading was very carefully considered as indeed I have a fan capable of being run from the 4V tap but decided that the 12V fan would be ok especially as Ed says, it is not intended to run the tester with a long duty cycle. For such tests then an external supply can be used.
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Old 11th Apr 2010, 10:57 pm   #307
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Les
Great neat work. I like the 'D' connector idea and will probably copy it, it should make wiring up more manageable and give better access.

Where did you get the 50 way ones I cant find any in Rapid, maybe I'm not looking in the right place

Frank
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Old 13th Apr 2010, 9:43 pm   #308
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Default Re: The "Sussex" Homebrew Valve Tester.

You should be able to get them from Farnell or RS like their 528-3581 but with those you have to buy 5 which makes it expensive. Don't go for the very high quality ones as these cost a small fortune, I know that at one time you could buy an economy version. If you have to buy 5 of the cheaper ones perhaps you can get others to chip in so the cost breaks down to single unit price. I just happened to have a plug and socket in the junk box.
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Old 13th Apr 2010, 11:32 pm   #309
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Les
Thanks for the advice.
You pointed me in the right direction.
I had thought of RS but as you said you have to buy 5 and they are expensive. I hadn't though of CPC until you mentioned Farnell.
CPC has 50 way ones at 71 cent per plug or socket and they sell them individually.

Thanks
Frank
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Old 16th Apr 2010, 10:16 pm   #310
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Frank, yes the cheap connectors should be fine here as one hopes that they will not be disconnected too many times when the more expensive ones would be considered. My biggest problem has been finding a reasonably priced enclosure, the one I had in mind may finish up too small owing to the size of the mains transformer. I will attach a sketch of something I had planned though the transformer limits the space for the valve holders but I only need 4 anyway. I suppose the transformer could be fitted inside a die cast box bolted on the back of the case, a solution maybe for anyone requiring more valve holders. The case I am thinking of is the RS 232-774 sloping front enclosure which is a Hammond 519-0920. A pity they do not manufacture one just another size up, the long gone Imhof-Bedco company did some splendid sloping front boxes which would be ideal if one could buy them today.
I still need to order the panel meters as well, it's just that so many other things have got in the way. I was hoping to make the panel marking a little easier by using number dials on all controls. I suppose that after a while one would remember what numbers to dial for whatever voltages were required. Just thought I would put it up here to see what the team think, it is just an idea but a sloping front case somehow appeals to me.
Les
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Old 16th Apr 2010, 11:11 pm   #311
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Les
Had a look at that case its a good one at a reasonable price but as you say its a pity that its not a bit bigger. I will attempt to do as Mike suggested and make an enclosure from MDF with aluminium panels, but that's a long way off yet
The panel markings are another problem and something I haven't had much successes with. Knobs are another thing that I am looking at now, because of the type of switches that I am using I will need collet knobs in both 6 mm and ΒΌ inch sizes.
It sure is a big project.

Frank
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Old 18th Apr 2010, 4:46 pm   #312
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Default Re: The "Sussex" Homebrew Valve Tester.

Thor, you have a PM.

Ed
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Old 19th Apr 2010, 12:28 pm   #313
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Guys,
Four months in, and over 20,000 views. I'm rather taken back by the interest shown.
Thanks to all who have helped in producing parts for the tester, and those taking the trouble to build one.
Is this a record on the forum for number of views in homebrew equipment?
Thanks once again for the interest
Regards
Mike
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Old 19th Apr 2010, 1:15 pm   #314
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Default Re: The "Sussex" Homebrew Valve Tester.

Mike,

My case arrived today so I'm mounting a few bits in. I'll post some photos as I progress.

Andy
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Old 19th Apr 2010, 8:53 pm   #315
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Default Re: The "Sussex" Homebrew Valve Tester.

OK
I've been busy today

I'm going to make a slight change. I'll use the pointer knobs on the front panel instead of the black ones.
I guess now the fun starts (wiring).
I've ordered a slab of aluminium (80mm x 20mm x 250mm) for the heatsink which I'll fix to the side panel and then fix the BUZ80's to that. I'm hoping to get away without using a fan.

Andy
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Old 20th Apr 2010, 10:47 am   #316
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Thumbs up Re: The "Sussex" Homebrew Valve Tester.

Hi Andy,
That does look cool (drool!).
I can't wait to see your final build and the unit fully working. Well done.

Regards

Rob
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Old 24th Apr 2010, 8:01 pm   #317
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Default Re: The "Sussex" Homebrew Valve Tester.

Top Cap, Take a look at the Hammond 1456-Sloped Aluminum Consoles ect... You may be able to find something closer to what your looking for.
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Old 25th Apr 2010, 3:20 am   #318
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Default Re: The "Sussex" Homebrew Valve Tester.

Could someone please explain the difference in rotary switches ? I understand the terms MBB & BBM but do not understand which is shorting and which is non-shorting ect... I have looked at most USA suppliers and none refer to them as MBB or BBM.
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Old 25th Apr 2010, 11:46 am   #319
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Default Re: The "Sussex" Homebrew Valve Tester.

MBB = Make Before Break = Shorting

BBM = Break Before Make = Non Shorting
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Old 25th Apr 2010, 5:11 pm   #320
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Default Re: The "Sussex" Homebrew Valve Tester.

Thank-you for taking the time to clear thing's up for me !
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