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-   -   Mullard Valve Tester Card Project (https://www.vintage-radio.net/forum/showthread.php?t=6112)

GMB 23rd Nov 2005 10:10 am

Mullard Valve Tester Card Project
 
I am undertaking to build as complete a catalog as possible of all the cards for the Mullard High-Speed Valve Tester. I am doing this after developing a really fast way to process the cards to obtain the map of their holes. But I don't have anything like all the cards and although I have tracked down quite a few from other people there are still many to go.

So if you have any cards for this tester and would like to help then go to this link for details...

http://home.btconnect.com/gmb/mullard.htm

Ed_Dinning 23rd Nov 2005 12:32 pm

Re: Mullard Valve Tester Card Project
 
Hi GMB, I'll have a look through the list for you; I also have details on adaptors. I've designed (but not yet built) a hole punch fot the cards.
It appears there were at least 3 versions of this tester as well as military one. All used the same cards but had internal circuitry differences. How about the CV range of cards, were they more comprehensive than the alpha/numeric ones?

Ed

Duke_Nukem 23rd Nov 2005 6:38 pm

Re: Mullard Valve Tester Card Project
 
1 Attachment(s)
I'd been putting off getting a list of my cards together, but I've finally got off my butt and done something about it ... list attached.

I have the test cards and a couple of others but can't seem to find them.

There are two versions of some of the cards (547,967b), differentiated by a letter A underneath the Mullard logo.

If you've generated a database of holes vs card, how about a utility to read the database and print out an actual size card ? I could have a bash it this if you don't fancy doing it yourself.

TTFN,
Jon

Colin 23rd Nov 2005 6:54 pm

Re: Mullard Valve Tester Card Project
 
1 Attachment(s)
Here's a list of all my cards. Simple colour code - Green I've got & Red I'm missing:)

Hope Excel 2003 format is ok. If not let me know and I'll let you have it in any format that's suitable.

rgds
Colin

GMB 23rd Nov 2005 10:57 pm

Re: Mullard Valve Tester Card Project
 
Quote:

If you've generated a database of holes vs card, how about a utility to read the database and print out an actual size card ?
Coming as soon as I have as complete a list as possible.
Quote:

There are two versions of some of the cards (547,967b), differentiated by a letter A underneath the Mullard logo.
That is something I haven't encountered so it will be interesting to see.
-------
I will contact you as soon as I have checked your lists against mine.

Duke_Nukem 24th Nov 2005 8:20 am

Re: Mullard Valve Tester Card Project
 
Quote:

Originally Posted by Duke Nukem
...and print out an actual size card ?

Quote:

Originally Posted by GMB
Coming as soon as I have as complete a list as possible.

Cool 8-)
Quote:

Originally Posted by DukeNukem
... There are two versions of some of the cards

I meant to add that they differ by just one hole, rather suggesting the first version was a bit of a monday morning accident.

TTFN,
Jon

GMB 24th Nov 2005 3:14 pm

Re: Mullard Valve Tester Card Project
 
I have updated my list based on the promised and actual contributions from a number of people. But still the list is incomplete!
So if you have a set of Mullard tester cards then please check http://home.btconnect.com/gmb/mullard.htm to see if you can help.

mikelect 24th Nov 2005 7:14 pm

Re: Mullard Valve Tester Card Project
 
I've got an incomplete set of CV cards. I will list them but don't have time at the moment. I'll be in touch when I have further news.

Mike.

Lowemission 28th Nov 2005 11:32 pm

Re: Mullard Valve Tester Card Project
 
Hi George

One of the projects that I was hopefully going to start in the New Year was to find out as much info about the MHST as possible, as there seems to be many unanswered questions.

Regarding the cards, over the years I've bought several lot's of cards and still haven't a full set :'( , but how many cards were produced ?
Does anyone have any later revised editions of the Numerical List, the latest one I have is number7, which I know is incorrect as I have cards which are listed as "no issue".

How many cards were Amended?, not all cards which were amended had the letter A on them. Later on I understand that Mullard called these cards "revised" cards, I've not seen one with the letter R on or did they stop marking them?
I have many duplicates and triplicates of card numbers, many having more than one hole difference, some as many as three or four holes and some of these with no letter A.
I've tried some of these cards on my tester which have had the same card numbers but with a different configuration of holes, the cards I used all gave the same readings.
Like many of you I've heard rumors about cards which suddenly make the tester go up in smoke 8-o , I'm not planning to do too many test's like this (mainly due to time) but I do suspect that maybe some cards were amended due to the old one causing problems.
I understand that these testers are prone to the odd transformer burn out, as far as I know it's not due to any one dodgy card.

Many amended/revised cards that were sent to dealers had an accompanying letter telling them to destroy their old cards.
I also understand that this "amended card service" had to be paid for by the dealer through a yearly subscription, wonder how many dealers didn't keep their subscriptions up to date so never had a set of up to date cards.

It wasn't until a while back when I started to go through my cards did I realise just how many discrepancies there were regarding card numbers etc, also that it would be a very long slow job.

I have two different MHST manuals, one being the early E7600 type which I will scan for you in the next couple of day's.

I have the military version of the MHST, model no CTA20, sorry but I have no info at all on it, does anyone?, could send you some pics if your interested.
This tester came with two boxes of CV cards, how many CV cards were produced, who knows.

This is about as much as I know, or it should be "don't know" about the test cards.

I'm sorry but I'm not going to be able to sort my cards out until well into the New Year.
What I had planned and will do is put a wanted notice in the BVWS free ads for any info regarding the MHST, someone must have more info.

Julian

Ed_Dinning 29th Nov 2005 12:36 pm

Re: Mullard Valve Tester Card Project
 
Hi Julian, I've got the valve/card list No 8, it is up tp approx 1175 card and is hand annotated to show cards to 1196(DY82) and 1197 (EL500). I also have details of the cards to be used when the unit was fitted with a Y8A base. This will also be copied to GMB as will the data on vards got, when like you I get some time to do it.
I had heard of the rogue cards/ re-issues, but not in the detail that you have given. I will have to check my duplicates to see if there are any differences. This of couse adds a who new dimension to card classification.
The way round the problem with possible transformer burn-outs that I have adopted is to fit 200mA fuses into each of the transformer taps that feed the HT selection.
I trust one of the Forum members will host all this data when it is collated.

Ed

GMB 29th Nov 2005 12:50 pm

Re: Mullard Valve Tester Card Project
 
I will be donating the final result to the BVWS and will probably host it too.

The issue of card revisions is interesting. I haven't encountered any of these and was not initially looking too hard. My own card set is quite old and obviously forms the core of the data.

Part of the project is to analyse the meaning of the cards so I will be able to verify that nothing in the database is going to cause damage. It will be interesting to see what changed on the revised cards - so I invite anyone with these to send me images of them even though they are in the "done" list.

Anyone coming to Wootton Bassett and who has instances of the missing cards but can't scan/photo them can bring them along and I'll do them there.

Paul Stenning 29th Nov 2005 9:38 pm

Re: Mullard Valve Tester Card Project
 
Quote:

Originally Posted by GMB
I will be donating the final result to the BVWS and will probably host it too.

It can certainly be hosted on my www.vintage-radio.info site if you wish.

Lowemission 30th Nov 2005 11:28 pm

Re: Mullard Valve Tester Card Project
 
Hi Ed, I'll get list No 8 off George when we exchange data.

Quote:

The way round the problem with possible transformer burn-outs that I have adopted is to fit 200mA fuses into each of the transformer taps that feed the HT selection.
Thanks again Ed, I couldn't remember what fuses you recommended.

Good news is that while sorting through a pile of service data tonight i came across another MHST service manual, this one is different from the other two that I already have, I'll pass them over to George to scan.

Julian

GMB 4th Dec 2005 10:55 pm

Re: Mullard Valve Tester Card Project
 
Many thanks to the people who have contributed so far.
After finding an unexpected 190 extra cards at Wootton Bassett to add to the database I have updated the missing card list at http://home.btconnect.com/gmb/mullard.htm.
But there is still a way to go - so if you haven't already done so, please check to see if you have some of the missing cards.

Paul Stenning 4th Dec 2005 11:05 pm

Re: Mullard Valve Tester Card Project
 
I have made this thread "sticky" so it stays visible at the top if the list for now.

ajs37 5th Dec 2005 10:42 am

Re: Mullard Valve Tester Card Project
 
Quote:

Originally Posted by GMB
Many thanks to the people who have contributed so far.
After finding an unexpected 190 extra cards at Wootton Bassett to add to the database

Hi GMB - I presume you don't need anything else from the cards at Wootton Bassett yesterday? I won the machine - if you didn't have time to check everything, let me know and I'll sort it for you -
Cheers
Andy

martin4 10th Dec 2005 11:02 am

Re: Mullard Valve Tester Card Project
 
We met at the last BVWS . Just a line on making cards I have tried many methods . Including formica, takes too long. The best and very quick is to cut your new card from the old green filing cabinet type files the ones with the metal top. You can cut out easy with scissors and make a punch from steel tube and use to punch out your holes. Easy. The card is just stiff enough to actuate the micro swith at the bottom.
Martin.

GMB 11th Dec 2005 9:53 am

Re: Mullard Valve Tester Card Project
 
Quote:

The best and very quick is to cut your new card from the old green filing cabinet type files the ones with the metal top.
I haven't seen other than cardboard ones but I presume there are some kind of plastic ones now?

It is worth noting that if you do have some good ideas for card material it must be able to happily stand 1KV across the thickness and be >100M resistance. Also, if it's a thermoplastic then you need to check whether it will get too soft from the heat inside the tester. There must be absolutely no danger of splitting or cracking as if you open up an erroneous hole in the wrong place it will cause serious damage to the tester. It is rumoured that even Mullard made errors and some genuine cards can cause damage - something that I will be checking during the compilation of the card database.

GMB 23rd Dec 2005 2:59 pm

Re: Mullard Valve Tester Card Project
 
Just a reminder to you all MHSVT owners who haven't got round to checking your cards - the latest lists are now up on http://home.btconnect.com/gmb/mullard.htm and will be updated over the Xmas holiday as and when I receive any further cards.

Merry Christmas!

GMB 4th Jan 2006 12:43 pm

Re: Mullard Valve Tester Card Project
 
To everyone interested in the history of the Mullard tester, take a look at this link: on eBay. It appears to be a hybrid of the early and later versions. Has anyone in the UK got this model? I have the early model which looks almost like this one, but the underside view shows that the EHT doubler has been added.

Colin 4th Jan 2006 1:03 pm

Re: Mullard Valve Tester Card Project
 
Mine's the same as this one.:thumbsup:

rgds
Colin

GMB 4th Jan 2006 4:11 pm

Re: Mullard Valve Tester Card Project
 
It seems that it was the E7600/3.
So does anyone have an E7600/2 or E7600/5+ ???

Ed_Dinning 4th Jan 2006 9:58 pm

Re: Mullard Valve Tester Card Project
 
Hi Gents, It's the first one I've seen with a hinged cover for the instructions, mine is the slide out type.
PS scans in post today George.


Ed

PJL 5th Jan 2006 12:43 pm

Re: Mullard Valve Tester Card Project
 
Mine is an E7600/4 model with horizontal buttons and having recently spent hours checking tolerance and replacing parts I now know it is an exact match to the Operating Manual Issue 4 (1958). It came with a test card index dated January 1966. Perhaps 5% of the 720 cards that came with it have the 'series' letters A or B under the Mullard logo.

GMB 6th Jan 2006 4:42 pm

Re: Mullard Valve Tester Card Project
 
In addition to finding all the cards we must also endeavour to find the latest revisions of the cards, especially as there were some pretty bad errors in the original versions. To this end I have now built a list of which cards submitted so far were revised.
So I am now asking everyone to check through your cards again, this time looking for revised cards.
And don't forget that we still have plenty of cards to find in any revision!
Details on http://home.btconnect.com/gmb/mullard.htm

GMB 11th Jan 2006 9:59 am

Re: Mullard Valve Tester Card Project
 
There has been some confusion about how to recognise a revision letter so I have updated the web page with an illustration.

Ed_Dinning 11th Jan 2006 12:39 pm

Re: Mullard Valve Tester Card Project
 
I'll second that George, I've had one of these testers for 20 years and only just spotted the rev letter!!

Ed

dave walsh 19th Jan 2006 9:52 am

Re: Mullard Valve Tester Card Project
 
I've got a HSV Tester in my northern location which came with two heavy metal trays full of cards. I will try and list them for you next time I'm at home but it may be two or three months. I've often wondered how many there are given the number of actual valve types that were produced over the years-cheers.

ukcol 12th Feb 2006 6:47 pm

Re: Mullard Valve Tester Card Project
 
Hi GMB

I have recently bought an E7600/4. The cards that came with it contained about 70% of those on your "Revisions" list. I have scanned them to JPEG. You have a PM.

GMB 13th Feb 2006 2:12 pm

Re: Mullard Valve Tester Card Project
 
Thanks to ukcol for finding the first revision "C" card.
We have started to reach the point of diminishing returns with this project as far as missing cards goes, but not for revisions yet.
We still need more of the military card sets to be checked as this is where we will most likely find the missing cards.

ukcol 18th Feb 2006 10:55 pm

Re: Mullard Valve Tester Card Project
 
It has been mentioned that some mistakes were made by Mullard when they produced the cards which can damage the valve being tested and/or the tester. Having just restored a 7600/4 to working order I have identified one such mistake. In the first box of valves I was testing I came across a PY32 which is a half wave rectifier with an octal base designed for television. The Mullard card index lists the test cards as 967 AB but when I pulled out the cards there were 3, that is 967 ABC. To have 3 cards is usually the pattern for a full wave rectifier. Card A marked ELECTRODE (to test for shorts) and cards A and B one for each anode to check emission. Cards A and B worked fine and the valve tested OK, but when I tried card B, I switched off quickly when I was greeted with the very unhealthy sound of a lot of current flowing. So if you have a set of 967 cards, throw card C away and change the number of cards mark on cards A and B to 2.

Ed_Dinning 19th Feb 2006 10:40 am

Re: Mullard Valve Tester Card Project
 
Hi Gents, this sounds like a MUllard "TRAP" if you obey the instructions and only use A&B all is OK, BUT presented with 3 cards the tester is likely to try to use all 3 with the results mentioned. I assume A,B,C cards are used to test a full wave rect with a different type number as well. These testers were often used by unskilled people in shops so I'm not surorised it caused problems.
This is probably the foundation of the warning about a rouge card that started in the 50's.
A worthwhile mod, that I carried out on my tester was to add fuses in all the HT transformer output windings (about 10 in all). These will then pop with a problem like this and prevent damage to an irriplaceable transformer.
The main trip and fuses will not always blow under these conditions.

Ed

GMB 19th Feb 2006 7:51 pm

Re: Mullard Valve Tester Card Project
 
The 967 example shows how important it is to get the correct revision of the cards, hence I now publish a list of known revisions. It is perhaps a pity that Mullard didn't think to duplicate 967B as 967C so as to ensure that the old cards were thrown away! The mistake seems to be down to this single diode having 2 pins for the one anode. You can see how this could have been mistaken for being a double diode. During tests of double valves the unwanted sections are often grounded out to avoid interference effects. The difficulty with this error is that it only becomes apparent when the valve is in the socket since the short-out flows though the valve base.

dave walsh 23rd Feb 2006 8:20 pm

Re: Mullard Valve Tester Card Project
 
George further to your recent pm, a quick trip north home reveals my Mullard VT as a 600/3. An even quicker run through the two tins of cards [with the help of my teen daughter] didn't reveal any of the special later items but from the missing list that you posted I appear to HAVE-

550 667ABC 715 721B 722 723 724 725 726ABC 727ABC 728 730AB 733AB 738 739 742ABC 744AB 745AB 746AB 747AB 749ABC 765 805 806 809 810 820 821 826 829 832 835 841AB 844AB 846 849ABC 851 852 855 856ABC 858ABC 863AB 864 866 868 869 870 871AB 872 873ABC 874 875 876AB 879AB 880AB 882AB 883 884AB 889ABCD 890 894 895 897 901 904AB 914AB 915 916 917 928 948 952 953 954 955 956 961AB 962 964 968AB 969AB 970 971 972 973 974 979 984 985 986ABC 987 989 990AB 991 993 994 995 1003 1004 1005AB 1007AB 1008 1009ABC 1010 1011 1012 1014 1016AB 1017 1021

Hope This might be of interest.

Dave Walsh Sussex

GMB 3rd Mar 2006 1:49 pm

Re: Mullard Valve Tester Card Project
 
If anyone else has some cards to add to the database then please note that I will be available at Harpenden on the 5th to photograph your cards.

Radio_Doctor 3rd Mar 2006 11:14 pm

Re: Mullard Valve Tester Card Project
 
Hi,
I am in the middle of going through six (don't ask) boxes of cards. I seem to have a few "A" revisions but so far none of your missing cards. I can't go to Harpenden sadly but will get in touch when I'm finished. Cheers,
Kneale

dave walsh 4th Mar 2006 6:41 pm

Re: Mullard Valve Tester Card Project
 
I am presuming that people know Alan Nunneley will do card copies [it says up to 10] on www.mullion-cove.com but of course there is a charge as it's his business. 6 tins is a lot. I was glad that my daughter helped me with two!

GMB 6th Mar 2006 11:18 am

Re: Mullard Valve Tester Card Project
 
The project had a good day at Harpenden with 11 new cards sets and 57 revisions found!

It has now become clear why the card sets vary so much - the deal was that you got your new tester with a standard card set plus 100 cards of your choice.

We now have 88.6% of known-to-exist card sets - so still looking for 125 sets and wondering why 103 were not issued.

For those who are waiting to check their cards, http://home.btconnect.com/gmb/mullard.htm is now updated.

Gordon 12th Mar 2006 9:41 pm

Re: Mullard Valve Tester Card Project
 
This French guy need a copy of the Operating Instructions in French. Does anybody know if these exist?
http://retro-forum.com/viewtopic.php?t=9069
Gordon.

GMB 17th Mar 2006 7:17 pm

Re: Mullard Valve Tester Card Project
 
1 Attachment(s)
Ed has sent me this picture of the pre-war Mullard tester, has anyone got a better picture (or even has an actual tester)?

plumbweiss 15th Nov 2006 10:29 pm

Re: Mullard Valve Tester Card Project
 
There are people around who make shellac-coated books for playing fairground organs. They generally have a foot-operated punch and use a folded thick card which is sprayed or painted with shellac after punching to make them hard, as the organ keys are strongly spring loaded fingers and the cards have to be repeatedly played without wear. Maybe worth aproaching them ? And how about fitting the HST with a socket for an interface to a digital relay output card from a PC? You could link this to a valve database and Im sure it could be done discreetly? They do this with fair organs too!!

GMB 20th Dec 2006 10:48 pm

Re: Mullard Valve Tester Card Project
 
I had hoped to be able to publish the results by now but I am still waiting for a number of people who have indicated that they should be able to make a useful contribution but haven't quite got round to it. Hopefully they will find the time over the Christmas break. ;)

While we are waiting I thought you might be interested in a few manuals and circuits that have been donated. Many thanks to everyone who has helped with this.

The various models of the E7600 all work in the same way but there have been a number of circuit variants implementing the same functionality. I think the manual of the military version (CT80) has the best description of how the tester actually works.

Also, the circuit diagram has been drafted in some very different styles so I put all the circuits I have found into one document.

You can find all this on my web site at http://home.btconnect.com/gmb

Merry Christmas!!

ecc83 7th Apr 2007 8:09 pm

Re: Mullard Valve Tester Card Project
 
I well remember being the "test jockey" as an apprentice. Prob' a stupid suggestion but since it is now possible to model electronic circuits on a pc can the testers circuit not be so modelled and then the "mission impossible" card situation avoided?
Dave.

GMB 7th Apr 2007 8:23 pm

Re: Mullard Valve Tester Card Project
 
PJL has somewhat done this and so we are hoping be able to publish the database with interpretation of the card.

However, modelling fatal situations not simply a case of modelling the tester itself as unexpected interactions with the valve can also be an issue.

PJL 8th Apr 2007 2:55 pm

Re: Mullard Valve Tester Card Project
 
Just to clarify, the effort has focused on calculating the test conditions from which an approximate 'real' value can be extrapolated from the deflection. I have personally found it invaluable.

Although some error checking is performed it is by no means exhaustive. It does allow modelling of custom cards but could only be used to verify your own design. Certain changes can be made with the card fairly easily and if there is sufficient interest I will document how to do this.

GMB 2nd Dec 2007 11:57 pm

Re: Mullard Valve Tester Card Project
 
Just when it seemed that things were slowing down another 100+ new cards turned up at Wootton Basssett. This has pushed the list of missing cards close to extinction and I am still awaiting a few more. There is now a real possibility to bag the entire lot.

So if anyone has missed this project, please look at the current state of play at http://home2.btconnect.com/gmb/mullard.htm and see if you have the last few cards.

(...and yes, this project has proved to be a lot more work than I had anticipated).

Electrical 28th Nov 2008 4:12 pm

Re: Mullard Valve Tester Card Project
 
5 Attachment(s)
Hello everyone, I have read all the posts on this topic with interest, as I too have been collecting sets of cards in order to build up a complete set of cards. I originally found GMB’s Mullard Tester Card Project by searching on Google about 18 months ago and sent off all the copies of the missing cards I had via email.
In one of the posts it was mentioned about rouge cards and I wondered if anyone had come across cards that have been miss punched as In the example of card Diode Test 1B, (AC/HLDD) where the holes are miss registered by approximately, 5mm, as shown in attached picture. In this case, the tester did nothing, as all the contacts in the gate switch were, held open, with the tester indicating an open circuit heater. Since I found this card, I always check to see if the holes are all in the correct place. I think you could imagine what would happen if the holes had been another 3mm miss registered, the set HT holes row ‘L’ would select the mains transformer secondary taps and would short together, with out any secondary fuses the mains transformer would have little protection and would probably burn out before you realised what had happened.
With reference to the card material, the original cards appear to be, made from 0.6mm (25thou) ‘Tufnol’, which in the ‘Kite Brand’ form has a very high electric strength. It is a Phenolic paper laminate, SRBP (Synthetic Resin Bonded Paper) and is available to order in 4 foot square sheets 0.6mm thick, or 0.8mm thick, off the shelf. http://www.tufnol.com. I have made blank cards from 0.8mm Kite Brand Tufnol and punched them on my jig, and have all worked very well. I cut the cards to an approximate size and a friend of mine milled the cards to the finished size of 8.25” X 5”, with the 1.5” notch in the side. At present, I have built up a supply of hundreds of blank cards, made from acquired scraps of 0.8mm Tufnol sheet, all I need now is copies of my missing cards to punch new ones to complete the set. My punch jig has a slide fitted on the top to allow me to copy a card by using the sample card as a template to reduce errors when punching.
One member suggested fitting a digital relay card to a tester and controlling it from a PC, well this may be another one of my follies but I have already built an interface consisting of 130 single pole relays, in 13 rows of 10 columns. Each relay coil is, switched via a transistor with a 15k resistor in its base and a suppression diode across the relay, operating coil. Please see picture. The interface is built, up from 13 separate PCB’s, with links fitted across the rows from A to M and the columns are linked across the top terminal blocks. As you can see it is not finished, yet and at present I am working on a diode matrix card consisting of 130 X 3.5mm jack sockets to program and test the relays. The matrix is fitted with a jig to slide a standard card in and by inserting a 3.5mm plug with a diode wired across the terminals, through each hole in the card will energise the appropriate relay and I hope will give the correct settings for the valve tester. Using this method of programming, a card for an unlisted type of valve could be set up by varying the positions of the diode plugs in the anode voltage set row ‘L’ and the grid bias row ‘I’ until the correct conditions have been achieved. To check these conditions I have built yet another jig, which consists of an octal plug and socket joined, together with 1 ohm resistor in series with the anode, screen and cathode pins, with pairs of wires across each resistor, which will indicate the current on a mili-volt range of a digital voltmeter. The anode and screen voltages are, measured with respect to the cathode, which on the tester is usually earthy. I did bring the grid connection out as well, but connecting a 10 mega ohm impedance digital voltmeter between the grid and the earthy cathode causes the spot on the tester to drop down to just about half way and there are signs of instability in the spot. I did intend to build in three small digital voltmeters into the tester to measure the parameters as each type of valve is tested, both voltage and current, but I will have to increase the input impedance of the grid circuit voltmeter first.
I do hope this post in not too long or not applicable to the original.

Regards Stan.

Ed_Dinning 28th Nov 2008 8:55 pm

Re: Mullard Valve Tester Card Project
 
Hi Stan, PM me if you need any prints of cards you do not have as I have about an 80% collection of cards and I'm in the area (I live near Stanley).

I'ts also worth fitting fuses in all the HT feeds from the transformer as it is a very complex beast that would be impossible to replicate. (I did one for the AVO 2 panel tester and that was very hard work).

Glad to se the project being revived again.

Ed

Electrical 28th Nov 2008 10:24 pm

Re: Mullard Valve Tester Card Project
 
Hi Ed, thanks for the offer, over the years I have collected 5 boxes of cards and at present I am short of about 215 cards. I checked this against my January 1966 Test Card Index list so I am sure there will be a few, more modern ones missing, as I am sure there must be a more modern list out there. I know the interface looks a bit big and cumbersome at present but at present I would like to see if the principal will work, that’s why I transistorised the relays so that if I ever get around to building a computer interface and find a way to multiplex all 130 relays the drivers are already there. When I connect it all up to a tester I feel sure there may be instability problems to solve first as I found when I built a jig to measure octal audio valves and applied a digital voltmeter to the grid. This is the reason I decided to make a simple diode matrix plug board to do the testing as I could end up with more faults in the computer programming and multiplexing, making it even harder to sort out. When it is complete and working, I will design a single PCB, with all the relays on an only use 400-volt 16A relays in the mains and HT rows. I am sure smaller 250 volt 7A PCB relays could be used in the base selection, so the size could be reduced considerably, also ULN2003 IC drivers instead of the resistor, transistor and diode drivers.
Dare I ask how far the complete list is off completion?
Regards Stan.

dave walsh 28th Nov 2008 11:24 pm

Re: Mullard Valve Tester Card Project
 
Hi all! Further to my post *34 [way back in 2006] sadly I have not done much to advance the cause since then. Are there any really rare cards in that list I wonder?
It's possible that I may sell of my Mk 6 at some point in the near future [in the correct section of course mods] as it's a bit like me having top flight guitar and not actually playing very much, or very well:-]!
If my cards were actually needed for a master index/resource available to others, I would want the tester to go to someone interested in co-operating with people like Ed or GMB and their projects.
I find that their is a lot of satisfaction in helping people to fill gaps with a particular interest even if you're not at the same level of competence.
Dave W


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