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Old 16th Jan 2010, 4:51 pm   #81
Ed_Dinning
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Mike, 35V at 50mA it is.
To keep the cost down I will make it a frame type with flying, colour coded leads. Leads will come out of one side only so it can be "drop through " mounted.
Angle brackets can then be used for upright mounting.
I'll post some pics when it is complete. Can you PM me your address please Mike.

Ed
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Old 16th Jan 2010, 4:52 pm   #82
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Default Re: The "Sussex" Homebrew Valve Tester.

Sounds super Ed, for safety - will the transformer have an internal screen or are you using split bobbins?
Les
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Old 16th Jan 2010, 4:56 pm   #83
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Les, it will be a screen, split bobbins give poor regulation

Ed
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Old 16th Jan 2010, 5:07 pm   #84
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Default Re: The "Sussex" Homebrew Valve Tester.

Wow Ed I never knew that. Now I know why Lab Power Supplies always seem to use the normal (if I may call it that) type of single over wound bobbin.
Cheers
Les
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Old 19th Jan 2010, 9:53 pm   #85
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Gents, here are some pics of the prototype transformer ready to go to Mike. It's not impregnated or over taped as it may need mods.
Size is 3 3/4" *3 1/8" and a 1 1/2" stack. It is 3" over the belly. FC's are 3 1/8" * 2 1/2"

Ed
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Old 24th Jan 2010, 1:16 pm   #86
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Gents, costings etc now completed on this transformer.
It works out at 50 including UK postage (collect from Newcastle if you want a discount).

Could those who expressed interest please re-confirm by PM and any other interested parties also. I will then order the materials and the transformers will be available in about 3 to 4 weeks time.

Best regards, Ed
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Old 24th Jan 2010, 2:26 pm   #87
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi,

I'm new to both this forum and this thread.

This looks fascinating...

Will there be a PCB manufactured for a group buy?

Andy
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Old 25th Jan 2010, 12:50 am   #88
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Default Re: The "Sussex" Homebrew Valve Tester.

Yes!

In about 3 weeks.

It will be 1.6mm fibreglass,
I've ordered 50-off etched only from P&M services, undrilled, to keep the cost down.

Price yet to be determined to allow a royalty for Mike, (but likely to be nearer 10 inclusive than free or 20...) and, hopefully, cheaper than buying the necessary photo-resist board & chemicals for a 1-off.

Martin.

Last edited by Dave Moll; 25th Jan 2010 at 4:19 pm. Reason: unnecessary quote removed
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Old 25th Jan 2010, 12:54 am   #89
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Smile Re: The "Sussex" Homebrew Valve Tester.

In that case you can count me in for a PCB and transformer.

Nice one !!
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Old 25th Jan 2010, 9:56 pm   #90
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Gents, when you PM me for transformers please include your postal address. I'll let you know when they are being sent off and you can then pay me by cash or cheque,

Best regards, Ed
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Old 25th Jan 2010, 10:25 pm   #91
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Default Re: The "Sussex" Homebrew Valve Tester.

Swordholder, could I get away with just two front panel meters?
I happen to have two Lascar single hole mounting panel meters, could I switch one to measure Anode/Screen current and the other Grid V/Gm or would this be inconvenient in practice?
Les
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Old 25th Jan 2010, 10:46 pm   #92
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Top Cap,
There is no reason why you have to have 3 meters. You can switch, but bear in mind that the GM meter measures AC millivolts to a resolution of 0.1mV.
Obviously the meter sensitivity will have to taken into consideration, again the anode current meter is a 199.9mv DC meter with a resolution of 0.1mV.
I don't know the Lascar meters, are they analogue or digital.
I used the 3 meters because (a) they dont need any switching and (b) they are relatively cheap at around 6 each including carriage on E Bay (see my previous posts for address).
If you do use the Lascar meters, you may have to alter values of resistors around the circuit.

Regards

Mike
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Old 25th Jan 2010, 11:47 pm   #93
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Default Re: The "Sussex" Homebrew Valve Tester.

Mike,

Is there any chance that you could produce a BOM for this.

Regards

Andy
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Old 26th Jan 2010, 9:36 am   #94
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Default Re: The "Sussex" Homebrew Valve Tester.

Andy,
I don't have a BOM, but the component values are all on the ciruit I published, any additions has been covered in my subsequent postings.
If you have any query let me know and I will try to answer your query
.

Regards
Mike
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Old 26th Jan 2010, 3:57 pm   #95
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Default Re: The "Sussex" Homebrew Valve Tester.

Mike,

Yes, I've gleamed what I can from the published threads.

I guess it's just things such as resistor ratings (1/8w, 1/4w etc) and capacitor voltage ratings, part numbers of the switches you used, etc. etc.

If I can get all the info I'd be happy to put a BOM together that anyone can refer to.
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Old 26th Jan 2010, 8:39 pm   #96
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Default Re: The "Sussex" Homebrew Valve Tester.

OK,

I have put together a basic BOM for this.
Things I am missing......

Valve bases
Most Switches
Resistor ratings
Capacitor voltage ratings

Feel free to tell me what I've done wrong and suggest ratings, switches etc.

Andy

Link to BOM

http://spreadsheets.google.com/ccc?k...pfMlE&hl=en_GB
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Old 27th Jan 2010, 12:14 am   #97
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by swordholder View Post
I used the 3 meters because (a) they dont need any switching and (b) they are relatively cheap at around 6 each including carriage on E Bay (see my previous posts for address).
If you do use the Lascar meters, you may have to alter values of resistors around the circuit.
That supplier presently shows no stock on e-bay, as does a firm I've used called Virtual Village. Maybe that's a temporary state of affairs. I hope so - these are great little meters, and as cheap if not cheaper than analogue meters, and being backlit, are nice and clear.

David,
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Old 27th Jan 2010, 12:45 am   #98
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Default Re: The "Sussex" Homebrew Valve Tester.

Dave,

Asia Engineer on Ebay have them in stock, I ordered a set today.

http://cgi.ebay.com/ws/eBayISAPI.dll...m=370325100729


Regards
Mike
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Old 27th Jan 2010, 1:16 am   #99
G8UWM-MildMartin
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Default Re: The "Sussex" Homebrew Valve Tester.

Andy,
Excellent!
A starter:
Add 2 1N4007s if using Ed's transformer, to make a bridge with D1 & D2,
D8-11 could be any 1N400x,
R2 dissipates about 0.75W, so perhaps a 2-watter, stood off the PCB?
Martin.
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Old 27th Jan 2010, 9:31 am   #100
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Default Re: The "Sussex" Homebrew Valve Tester.

Andy,
The majority of the resistors (apart from the one Martin mentioned) are 0.6w MF fron Rapid electronics
Switches are
2 x 1p 12w Make before Break rotary switches (Rapid Electronics 79-0100) Anode/G2 volts
1 x 3p 4w rotary switch (Rapid Electronics 79-0222) Function switch
10 x 1p 12w rotary switch (Rapid Electronics 79-0220)
(A1/A2 sel + pin selectors)
Relays are
Relays 2 x 48v low profile 8A (Rapid Electronics 60-4854 or similar
LEDS
LED1 Standard green LED
LED on relay board Standard Green LED
LED2 LED3 Low Current red LED (Rapid Electronics 56-0430 or similar
Hope this helps.

Regards
Mike
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