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Everything posted by STEVE

  1. Any one have any experience with PICs? I want to test 16 diodes at once.
  2. I am looking to build the PIC diode tester described on the site. I would like to expand the project to test more than one diode at once. Looking at the schematic it looks like it uses 4 outputs and 1 input from the 16F84. Looking at the datasheet for this PIC, I could expand it to test 2 diodes at once as the PIC16F84 has 8 outputs and 5 inputs. Although I would like to test more than two diodes at once, are there any PICs out there that have more outputs and inputs? I could just use a bunch of PICs but I think it would be a neater solution if I could just use one or two PICs. Thanks in advance.
  3. This may already have been answered on previous pages ... but don't have time to read all 19 at the minute! In the power supply which supplies the +/- 5 V (schematic attached) what are the two 1 K resistors for? Thanks
  4. http://www.osioptoelectronics.com/products/02-07_PDiodeChar_OSIOpto_0.pdf "To form an ohmic contact another impurity diffusion into the backside of the wafer is necessary. The impurity is an N-type for P-type active area and P-type for an N-type active area."
  5. Found the answer ... It's an ohmic contact to reduce the resistance between the semi-conductor and the metal contact.
  6. On a photodiode does anyone know what the N+ region between the cathode and the N substrate is for? Thanks in advance!
  7. Would anyone know how to go about designing a circuit to decode the MSF signal from Rugby (UK) to create a radio controlled clock? I would like to create a project displaying date and time using the signal transmitted from Rugby. Thanks in advance
  8. You could also introduce a small circuit which indicates when the IR beam passes over the photodetector. Circuit consisting of an Op Amp and an LED (visible one!) for the output. Attach the input of the Op Amp across the photodetector, turn the IR diodes on, try directing the IR diode towards the photodetector. The visible LED will light when IR beam hits photodetector. Probably a bit more complicated than just using your camera but still another way of doing it!
  9. I thought I would post this .pdf as I think it's quite good and explains op amps really well. It explains them right from the beginning through to complicated stuff like active filters etc... Let me know what you think! [attachment deleted by admin]
  10. Hi Stephen, I know that the idea you have already exsists.
  11. Just thought I'd share this with everyone coz I thought it was pretty amazing! A tiny ScanDisk memory card (256 MB) for my mobile, will miniaturisation ever find a limit?
  12. I have just been browsing on RS and found that they have information on the changes to Pb-free solder: http://rswww.com/cgi-bin/bv/browse/[email protected]@@@[email protected]@@@&BV_EngineID=ccciaddedddhimfcfngcfkmdgkldfim.0&cacheID=ukie&Name=weee&logText=uk2043&logType=109 Steve
  13. I'm haven't seen the affects at first hand of what happens when the two solders are cross-contaminated, but perhaps there won't be much chance of this happening as everyone will have to use lead-free solder and Pb solder will become obselete ???
  14. (couldnt work out how to attach two files at once!!)
  15. T flip flops and D flip flops are just JK flip flops with inputs connected slightly differently. I have attached schematics of each type of flip flops. Whether you can convert them depends on how close you can get to the inputs of the JK, I think this would be impossible if the flip flop you're using is on a chip, as they usually only allow one input - either D or T.
  16. I thought I would post the implications of Pb-free soldering I have found on an industrial scale. This is more for interests sake but also to see if anyone has found similar attributes in a more 'domestic' setting. Issues which can arise are: the flux used; corrosion of equipment; higher soldering temperature considerations (on components, and in industry board sagging) and fillet lifting. Dependant on the composition of the Pb-free solder the flux may have to be changed to a water or chloride based flux. This new flux can start to corrode the boards after a while if it isn't cleaned off (hot water can clean it off - just make sure you haven't got the board powered up when you clean it!! :o). Another effect the new solders can have is they can corrode stainless steel. I don't think this would have much effect in the 'domestic' setting, in industry some of the equipment used for wave soldering etc. contain stainless steel parts. You may have to be careful about raising the temperature too high on your soldering iron incase it starts to damage IC's etc.. In industry they also have to be careful about how high a temperature the boards are heated because they start to sag - too much sag can be bad news. Fillet lifting is another concern when using the new solder. If you want me to explain what fillet lifting is let me know. Ways to reduce it include: Avoid the use of BISMUTH (Bi) containing alloys; Avoid lead contamination into lead-free alternatives; Increase the cooling rate immediately after soldering. Like I have said I have only really researched into the industrial implications of Pb-free soldering and I have no experience in the effects for 'domestic' soldering. I'd be very interested to know if anyone comes across any of the problems I have mentioned above. Thanks ;D
  17. I don't think that anyone has started a topic on this as far as I can see ... I was just wondering whether anyone had any experience with using lead-free solder yet? There have been various directives put forward by the European parliament, such as the RoHS (Restriction of certain Hazardous Substances) and WEEE (Waste in Electronics and Electrical Equipment). Basically the lead content in solder is to be reduced to something around 0.1% (current solder contains about 60%). I have done a little research into the area before but only really on the industrial implications and I'd be interested to see if any of the problems found in industry are such big problems on a smaller scale ... Let me know if you have had any experiences Thanks :D
  18. Woopsey !! I'm afraid I've told a bit of a fib ... I have just finished dismantling the dimmer and lights. On closer inspection the 6 spots are infact low voltage halogen lights cunningly disguised as mains spots (they are hidden in behind frosted galss). They are 12V 10W bulbs (6 bulbs = 60W) the dimmer range is between 60W - 400W. I think this is the reason for the flickering its right at the lower limit of the switch. I checked the triac and diac and they seem to be working fine. I'm now thinking that I'm going to have to put a resistor in series with the lights. I'm guessing I should try and raise the circuit power consumption to around 200W. So what size of resistor should i use (resistance and power rating ... )?
  19. Yea they are still dim when at maximum brightness, how would I test the diac & triac to see if they are working correctly? One of the bulbs has just blown !! I'll have a look at the power rating of the switch and the wattage of the bulbs attached in the morning (on GMT here!) thanks
  20. I have recently installed a dimmer switch to control a circuit of 6 lights (spots) running off the mains (not low voltage lights), but when the dimmer is switched on the lights continuously flicker. It's as if the switch isn't sensitive enough. Is there anyway of adjusting the switch so that I get no flicker? I had an idea of putting capacitors across each of the lights to smooth the voltage out but am unsure if this will work ... ??? Any ideas would be much appreciated Thanks
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