EdwardM

Hi fotoobscura, interesting handle and even more so project. If I can throw my $0.02's worth in, my first thoughts are that a series of 4/5 LED's+resistor+battery could be put in per bubble and could have a lifetime of several weeks, but I think that at the ranges involved, the LED's will do little more that mark their own positions and not provide any sensible amount of illumination for the artwork. An alternative but more expensive solution would be to have a battery + inverter + small fluorescent light per bubble. The light output from fluorescents being much greater, could be greater still with a reflector 'behind' the fluor., Iguess this could be arranged because line of bubbles is effectively fixed and a small weight fixed underneath each would provide a 'down' direction. Is the budget huge enough for me to come over? any good hotels? Seriously, an interesting project and I wish you well with it! Ed Forgot to mention: If you go for fluorescents, the bubbles can of course be colored blue :)

Hi scuba14c the warnings section (page 70) of the app-note I mentioned earlier gives at least a partial answer to your last post Best of Luck Ed

Hi magatru Good site!, I may need to use it myself soon Best of Luck Ed

Hi scuba14c apart from the HV switch, the inductor design is about the most important part of what you're trying to do, can I suggest you have a look at http://www.semiconductors.philips.com/acrobat_download/applicationnotes/AN96052_1.pdf and particularly the section on inductor design Best of Luck Ed

Sorry scuba14c, I get errors when trying to open your JPG Ed

Hi scuba14c can you describe L1 in more detail or post a photo? Ed

Hi All MP, forgive me if I take you slightly out of context, but can't agree with the statement that the site should be considered a failure. I've looked at many community sites recently and this is the ONLY one which consistently has about 20 guests/members on-line at any given time. Look at the number of views on any topic, even the most obscure has 40 or more and the more popular topics running into thousands of views. Of course there are many people who are unwilling to post, either from a fear of looking ridiculous or from not feeling they have *enough* expertise to contribute. Clearly there are at least 8980 members who might like to post but don't do so for these and other reasons. One of the beauties of this site is that flaming is almost unknown here and so should encourage anyone to contribute. Alll the Best Ed

Hi Alun couldn't agree more, the loonies are taking over the asylum Ed

Hi audioguru here in the UK we've recently had a law passed that only licensed electricians can work on many types of home electrics. In all the houses I've had over the years, the only wiring problems I've found are those caused by licensed electricians! AAAAArgh ::) Ed

Hi MP and everyone I likewise don't see a problem with posting in the wrong area particularly as some projects take in many disciplines and it's often not immediately obvious which way a thread is likely to expand, really it's down to the moderator to organise as they see fit. It's not uncommon to see MOVED but you're always able to find where the thread has gone. I've posted in other forums on the net where I thought I had some knowledge/expertise and in one site in particular was almost immediately flamed. Possibly the 'not invented here syndrome' was operating so I've tended to stay clear since. How much more difficult it must be for someone whose first language is not English to stand up and say "I don't know, can someone help", it's one of the beauties of this site that it can be done and whilst we (I mean I) don't always get the answers right, at least we try. I'm sure also that there are many of the thousands of members who would like to respond to queries but don't because of what they percieve as their poor English, it shouldn't put them off. I've seen many posts start off with "please excuse poor English", I'm always tempted to reply with "please excuse my non-existant (insert your language here). Long may this site continue. All the Best Ed

Hi Aun The site mentions 40 something volts ac, being a uni site means there's probably some integral calculus going on ;D Just to add to what you've said, I've never had a bad shock (well 1, more later) and that's because I had a good teacher - he advised that I keep one hand in my pocket when doing anything where there was a possibility of high voltage being present. The only painful one was a bit odd: I'd spent some time trying to solve a power supply problem in a satellite receiver out in my garage workshop but left it as I had to move on to other things. Anyway, about a month later I was at a loose end and decided to have another look at said receiver. You can probably guess what happened next... I picked up the circuit board with both hands (it wasn't connected to anything) and jumped a foot or two and probably said something mild like oops. The reservoir capacitor had obviously retained a *lot* of its charge from the previous power-up. Ever since I've been even more careful, even when something hasn't been plugged-in for months! Ed

Hi Folks I just checked the Manchester University, Dept. of Chemistry site and they say: Voltages in excess of 50 V can be lethal Which confirms what I was taught many years ago when at Radio college. Ed

Hi Ante too embarassing, thats my normal standard of construction. Next time I build one I'll try to remember to post! Ed

Hi Abu there was an excellent article published in Elektor magazine in July 2004 entitled light sensor technology (measuring daylight using LED's). It is worth trying to get a copy, if only for the impedance converter circuit which has an input impedance in the teraohm region. Author was K.J.Thiesler and according to the mag the download number is 030435-12 and available from www.elektor-electronics.co.uk/dl/dl.htm Ed

Yup Ed

Hi zosh the emitter is the pin nearest to the metal tab sticking out from the body Ed

Hi magatru from the sound of it, the replacement battery is probably faulty and is not charging fully even if the PDA says that it is charged. To answer your questions: 1. There are counterfeit goods around, I don't know. If you got the battery from a reputable source then it was probably OK 2. mAh is a measure of the capacity of a battery to deliver current for some length of time. In your case, 950mAh means that the battery should deliver 950mA for 1 hour or 95mA for 10 hours or 9.5mA for 100 hours. To measure the fully charged battery capacity you need to do two things, first you need to connect it to a circuit which will measure current and voltage at the same time and then connect a resistor which will cause the battery to discharge. A circuit is shown below. The idea is to make a note of current and voltage at fixed time intervals and then produce a graph from which is deduced the mAh figure, this is a tedious process and should really only be undertaken if all else fails. 3. The measurement I've just described can be done automatically by a datalogger, this is a machine which at fixed intervals, say every 10 seconds, will record voltage and current for you instead of you writing it down. The PDA forum you mentioned, perhaps you could post details of the DIY tutorial. Best of Luck Ed

Hi http://service.semic.sanyo.co.jp/semi/ds_pdf_e/LA6541.pdf Ed

Hi V8meathead Several EPROM's are sometimes used in a system, this is why you find the pins /E and /G, the / means that they are active low (confirmed also by the small circle) and are used to (/E) enable a particular chip so that it can be read from or whilst programming, can be written to. The /G is an output enable. Normally all EPROM's will have their /G pins connected to 0v and the /E pin enabled individually so that data from only one chip will be output onto a common databus. This means that for every EPROM in this system every Q0 is joined together and all Q1's etc., forming a databus. Whilst the /E input is high (=1) data out is tristated or invisible. Whilst there are many other ways of doing this, consider what would happen if you had programmed the bit pattern for a 7 segment LED as data in each of the lowest 16 addresses? If you address location 0, the bit pattern could be used to show 0 on a display, location 1 would show 1 and so on... It's also possible to program quite complex test sequences using a single EPROM, imagine a parallel counter which is attached to the address pins of the EPROM. At each clock transition, the address increases by 1 giving a different byte on the data output - that byte is then used to do something with other logic and can inhibit the clock until the system is ready for the next address. Hope this helped Ed

Hi Kasamiko take a look at this Ed http://www.emcesd.com/1ghzprob.htm

Hi V8meathead sounds like you've worked it out already Take a look here: http://xtronics.com/memory/how_EPROM-works.htm Ed

Hi Muhammad Abu Bakar try this http://www.semiconductors.philips.com/acrobat_download/literature/9397/75014374_micro.pdf Best of Luck Ed

Hi magatru The first question I have to ask is: are you sure that the replacement L- Ion battery is fully charged? as within reason 950mAH is the same no matter which battery technology you use. I've done a net search of PDA's and some specify that either L-Ion or L-Polymer can be used. If the substitute starts fully charged and only gives 1 hour of life, does an original battery give full or the same length of time? To measure mAH, you need to at least be able to measure current using a multimeter, ideally you should use a datalogger as the power consumed by the PDA will vary greatly during the discharge cycle. Lastly, provided that both types of battery use the same connector scheme, there is no reason to harm the PDA. Hope this helps Ed

Hi Xenobius I'm half-awake now - my usual state - but was thinking if you need to do more than a few coils, one way is to take a round plastic rod, taper the end of it and machine a spiral groove into the taper of the correct number of turns - its then easy? to produces lots of copies Best of Luck Ed I can't think why I said "groove", I meant to say flat. Also, if the wire is wound tightly, just realeasing the tension slightly should be enough to slip the spiral off the rod.

Hi MP I'm aware of the differences between and advantages of mag pickup, if you check back the posts, what I've done is provide one possible solution to moeburns' original question and hopefully given food for thought. ? my problem? On your point about diffraction and vertical movement, it's a good one and the cmos/ccd sensor in conjunction with DSP could provide a solution by measuring the rate of change of shadowing since the sensor is a nice mixture of analogue and digital technology. Digital in terms of position and analogue in that an analogue voltage is produced in each bin. All the Best Ed