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Everything posted by SM2GXN

  1. 150/Freq(MHz)=Dipole length in meters I would say that quarter wave dipoles are very very rare.
  2. Hi Cryonic! Couldn't have said all that better, I've built receivers, transmitters rf-amplifiers guitar amps with tubes, few things give such a pleasure as looking into a glowing tube if lucky some blue colour slips out from the holes in the plate and they even smell good
  3. If your wish is to start by building an RF-amp check the attached PDF-file VHF-UHF_Amp.pdf
  4. Hi sssaaa! As Staigen correctly stated, a good antenna for the band to cover is the best way to start. A good advice is, make som kind of rotatable antenna and add an RF-amp for weak signals that is just above the noise level.
  5. Hi Um...Me123! If the current consumed by the load not exceed 1A you can chooose any of 1N4001-1N4007
  6. What's cloggies? Some electronic device? Ante will cloggies fit into that kind of climate we got in northern Sweden? ;D I've found the programmer when I was cleaning my lab I'll post it on monday with printer port cable and a dil-socket, finally!!
  7. Hi Mukhalled! Here's a PDF-file I had on my hdd "AUDIO AMPLIFIER ICS DESIGNER AUDIOIC.pdf
  8. Hi shaiqbashir! For your first question, the voltage rating given for a capacitor 16V/1000uf means that its maximum working voltage is 16V which you shouldn't exceed, they may withstand higher voltages than the one marked on the capacitor for a shorter period of time but it is always best to stay lower otherwise POFF!!! ??? As you may have noticed, higher voltage rating is equal to bigger can, usually it is as simple as this: you don't put a 50V/1000uF in a circuit were the maximum voltage is 10 volts cause they cost more but if the only capacitor you got on hand is 50V/1000uF just plug it in :) it will do no harm in most circuits, the can may be bigger so space could be an issue. For your question number two, in most cases there should be no problem to replace the 12V with 50V capacitor having same capacitance, there may be circuits sensitive enough to upset the function but rarely. If you don't find the proper value for your capacitor series and parallel is the alternative, one might not be able to get exactley same value but often close enough.
  9. Hi Felto! Can you take a picture of what you think is a transformer, it would help a lot. If there is a motor inside running at AC the load wont be purely resistive either, we have to take into account or? ::)
  10. ;D ;D Honestly I liked the old "S" marking better, this CE and all the other labels they put on all electronic devices means nothing to me, you don't know if they just have a big pile of labels in a box and when they think it's ok they just put on theirs product, not to talk about EMC it's a big joke ;D Ooops!!! :o
  11. Hi Ante! Well it's -2 to here so it's time to switch on the A/C ;D I don't think so it might have got in to Sweden by the "unknown black freighter" ;D I don't remember but not much current passes through those switches, maybe 2-3 amps (as you were guessing) I was more worried about the maximum voltage. yes indeed it is bad engineering at highest level, here's what I did I bought another thermostat from Elfa 37-920-09 and some silcone rubber, made a small box with double sided pcb over the blanket thermostat and filled it with rubber silicone it took nearly 2 weeks to dry ;D but it sure works.
  12. Hi! Here's some thoughts :) My curiosity lead me to open a rubber block containing the thermostat on a heater blanket that didn't work well, the blanket which is made of rubber is used to warm up a R134a refrigerant tube for car A/C in order to speed up the refrigerant R134 transfer from the tube you simply wrap it arround the tube. The blanket is made in just about the same manner as floor heating but wires are much closer to get a more even spread of the heat, I think:). Inside the rubber block I found 2 thermostats in series, started to check for data sheets on the web and found them 120VAC 6A for each, check this link: http://www.elfa.se/pdf/69/06937981.pdf. Now, what do you think? Did the designer put these thermostats in series in order for the blanket to work safe on 230Vac or did he just do it for fun? I belive that there are no thermostats that will close and open exactley at the same time even if they are pretty well matched, I'm talking bimetallic thermostats. My conclusion is that one of the thermostats will have to take the whole mighty 230Vac cause they will not close nor open at the same time. This blanket is made in US, could this version with two thermostats in series be for countries with 230Vac? :o Let me know what you think...
  13. Yeah Ante that's true hams like to solder on the copper side. During the etching you discover that you've forgot to mirror the layout so what does it men? All components on the copper side ;D
  14. Here's some pdf files containing marking codes for SMD,s and some hints. Found them while cleaning up my HDD ::) SMD_Codes.zip
  15. Thank's to Staigen and some dirty detecive work 8) we solved the problem with the login problem, without Staigen I wouldn't have solved it. He is a real hacker ;D
  16. SM2GXN


    Hi mettula! A shematic is always a great help and amplifiers with two equal channels is also a great help when you are into fault finding cause you can compare the signals by following it's way through the two channels. 100hz in your sub amp sounds like a bad filtering or that something have happend with your input stage, measure for dc at the output of the amp there should be no more than tens of mV, there could be a few decoupling and filter caps in your amp so where they are is not that simple to say unless you have schematic to upload. If you have a scope it is much easier to check for open capacitors in the way of the signal but another way of doing it is as EdwardM mentioned in his post. What brand is it and do you have any schematic?
  17. Hi pilottx! Interesting project, in another thread there is a discussion about a RPM counter using single IC LM2917, inside the IC there is a comparator which can be set to trigger at 3000 rpm (if I undeerstood the data sheet right) and activate the air valve. Let's see what the output of your ECU will show :)
  18. Hi Ante! What is the problem?
  19. Hi alkv23 ! Nice lab you got there, a clean bench is what I always wanted to have to
  20. Simple and useful circuit. Last winter I started a project to make a camera for winter fishing ;D the idea was that the camera could be dropped down in water under the ice to see when fishes approached the bait but it's still a project ::)
  21. Hi! I'm about to repair a battery charger made by Makita model DC1411 with blown mains fuse. Found a shorted diode which seem to be part of the snubber network. Marking on this diode hard to see think it is H8V.93 but not sure, there is another diode on the secondary side having similar marking H6V99 Anyone seen any of those or know how to get data on them?
  22. Had only one manual close by an old Sony CCD-F350 B/W view finder, seems that it should be no problem to fed composite video right into the view finder board, all voltages for the crt are created there so for this view finder only 5V is needed. For the LCD,s I don't know. Hi Ante! How's things going? Does the TRV11 or TRV30 have B/W or colour view finder?
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