1st October 1997Many thanks for the latest EUG #33 and the corrupted disk. It was good of you to try and fathom out/recover the disk's contents and I appreciate the remarks from Robert Sprowson about the problem but as the person in question is happily soldiering on with new set up, I've decided not to waste any more time on it. In passing though, I also suspect that there is a partial fault with the DFS chip, as Robert suggested.
I have decided to upgrade from my A3010 to something more modern and fancy. The new A7000+, which will do for me when fitted with a SCSII i/f. To help fund the upgrade I have cleared out the attic of all the old stuff and am in the process of cataloguing it. There is loads of Elk stuff plus bits for the BBC, Master and PC and some unusual items from my broadcasting days. In view of this, I am submitting a Classified Ad for EUG #34. By the time it appears, the lists will be printed out and I'll send EUG the first one off the press. In the meantime, one more item for EUG:-
Having acquired one of the newer digital cameras (surprise birthday present!) I was appalled to find out that they sell the AC adaptors separately - and at an exorbitant price of £60+. Surely this is a bit of a rip off as I bet I could build a regulated DC supply for less than a tenner, which I intend to do. Before I stick the end into my expensive toy, I thought I'd better make a few enquiries regarding these adaptors. Have any members had experience, bought one, or know if there is anything special about them? The spec. only states 6.5 - 7V DC, but no current consumption figure, but I suspect it could be as much as 1 - 2 Amps. The camera is run from 4 AA cells and, according to magazine articles, the biggest drain is when the 2" screen is on and during transfer to a computer. Any information would be much appreciated.
Keep up the good work.
Del Williams
Regarding your camera. Would rechargeable batteries be too inconvenient?
Maplin sell NiMH AA cells for just £5.49 each. These are better than NiCad, which tend to have the dreaded memory effect. The charge in my experience lasts a lot longer than with ordinary batteries and, of course, you can re-use them hundreds of times. I am not sure what sort of charger they need but I will look into it. Think carefully however before spending tons on a super duper charger which does everything you don't need or equally a cheapo which will shorten the battery life to about fifty charges.
You will probably be best getting 8; 4 to use and 4 for spare. And at the end of the day, with a capacity of 1200mAh, you may get better battery life without the inconvenience of a mains adaptor.
I have a little experience of mains adaptors for high tech equipment partly from some servicing work and also from my 386 notebook PC.
On my 386, the power plug is in fact a 5 pin mini DIN plug. The power comes down two lines as normal but there is also another two lines used as a signal and return path. So the power comes into the computer, sends a signal up the signal path, this is returned down the other path and the computer works fine. No signal path and the computer will turn on but the hard drive doesn't work properly and did eventually corrupt itself. Soon after the power switches the computer off.
I checked inside the power pack and there is only one 5V + and - line, no -5V or 12V but some circuitry for this handshaking signal.
This was used by Commodore on their 8-bit machines with tape drives. The shops told people that an ordinary tape recorder would 'blow' the computer. In fact, there was a handshaking line which was connected to a micro switch under the Play key on the tape recorder. If this micro switch did not connect these two handshaking lines at the same time as the Play button was pressed, the computer crashed. The solution was to rig up a switch and to turn it on at the same time as the play button was pressed.
Sadly my notebook PC and other "high tech" equipment which I have seem to want an elaborate signal.
Now all might not be lost. Firstly what sort of connection does your camera need? Is it a power plug? If so then chances are there isn't a handshaking signal needed, though one might be expected modulated onto the power line itself.
Do you know the polarity? This is important because despite the cheapness of a diode to protect against wrong polarity few manufacturers put one in. If you don't mind me saying, the current consumption is unlikely to be a large as 1 to 2 Amps since using AA cells they would get really hot. Remember 2 amps with 6V this would be 12W.
I once had a 12W soldering iron which burned its way through a carpet belonging to the mother of a girlfriend who I had hoped would solve all my problems. No-one would believe me when I said that I had re-arranged the lounge to make better use of the space and they were not impressed when they discovered that in the process of re-arranging the china cabinet, a spode plate had slipped and crashed onto a spode cup and saucer. A tangled web indeed.
But I digress.
Gus Donnachaidh, EUG #34
