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  1. OLIVE2222

    LED grid design

    Hi Kerberus, For "random" displaying you can use counters for the row and column driving. For patterns you must go for a small microcontroller (PIC, ATMEL, ...) Just use led Matrix as the keyword in place of led grid and google will show you the way. Olivier
  2. OLIVE2222

    Help with PCB design... I'm becoming insane! Please help!

    I suggest to google a bit with query like "Eagle library tutorial". I don't know which cad you decide to go for, eagle just looks very popular. Indeed such software's can be hard to learn but for simplest projects, design libraries is probably the only obstacle. Olivier P.S. I use...
  3. OLIVE2222

    how to make buzzer only beep once.

    Hi Doug, The 74121 is indeed functionally equivalent to the 4528 (no slap so :) ) . But he is not a CMOS type, mean he will draw more current from your batteries, better to go for a cd4528 or 4538 so! Olivier
  4. OLIVE2222

    One switch two light bulbs.

    Hi Dave, Yes I have read the sad Ronald story to the end, that's why I was a little bit embarrassed with the littledavyboy reply. Olivier
  5. OLIVE2222

    Basic Electronics

    Hi want_to_learn, Welcome to this forum! It' all depend of what a lot money mean to you. I know a TV repair shop with guys they live decently. Mean they have a place to live, a car, they can feed they family and they go in Holiday time to time. Today it's look like many mass market product...
  6. OLIVE2222

    how to make buzzer only beep once.

    Hi, welcome to this forum! You can use a so called one-shot circuit to achieve that. See my little sketch. The datasheet ot the used componant is here: http://www.bucek.name/pdf/4528.pdf The unused monostable pin's are to connected as on fig10 I keep the "odd" connection of...
  7. OLIVE2222

    One switch two light bulbs.

    Davy, Happy that it's what you are looking for but the design is absolutely not mine. I just point you to the right direction! Doesn't mean that I am not a great guy too:D:) Olivier
  8. OLIVE2222

    One switch two light bulbs.

    Hi davy, If you talk about main powered light bulbs this is the trick: http://www.dos4ever.com/keukenlamp/keukenlamp.html Olivier
  9. OLIVE2222

    Where to get PCB parts?

    Hi wespalladini and welcome to this forum. The PCB looks nice but valve projects are not the good way to start electronic DIY because of the high voltage present on the board. As you start the component cost is also an issue, better to blow a few cent semiconductor then a highly priced valve or...
  10. OLIVE2222

    Crystal Oscillator Circuit.

    Hi cjdelphi, You will find the theory behind the circuit and how the crystal is acting here: http://www.electronics-tutorials.ws/oscillator/crystal.html Olivier
  11. OLIVE2222

    Smart hearing aid circuit that doens't work

    Hi, Nice to see detailed post and annotated schematic ! Electret microphone's include a fet transistor for amplification purpose. It' s described here under. http://en.wikipedia.org/wiki/Electret_microphone You can't get it working by connecting directly to a loudspeaker. That what the...
  12. OLIVE2222

    Differential Op amp CMRR

    Hi Pump, Welcome to this forum. Differential op amp can be build on various way by using 1 to 3 op amp. The CMRR is frequeny depending. If your desgin is theoretical you can be in a perfect world an choice the 1 opamp design with very tight components specifications. Practical design would...
  13. OLIVE2222

    Help with PCB design... I'm becoming insane! Please help!

    Indeed you need to learn you to draw your own footprint with your CAD package as the "standard" footprint library will may not fit your needs. But before drawing your footprint you can have a look on the web by using query like "eagle PCB library" and you will find toons of them. Another...
  14. OLIVE2222

    Frequency ?

    Hi, With such frequencies you can use a main transformer to go to a lower voltage then by using a diode bridge you will have a (not stabilized) ground referenced 100Hz signal. Then it's all depending of the final application. With a comparator you can obtain a 100 Hz squared signal. To go to...
  15. OLIVE2222

    isopropyl alcohol leaves residue...

    A pcb mounting sub-contractor we are working with is using acetone after the soldering process.
  16. OLIVE2222

    Capacitor ID

    Not sure that I catch everything but: Normally you can connect the amplifier directly to the loudspeaker, knowing that in the case you lose the protection part of the passive crossover. They should be very few components in the passive crossover so maybe it's worth to repair it. Regarding...
  17. OLIVE2222

    Frequency ?

    No help possible with so few information's. which frequencies? which voltages? which current? which purpose?
  18. OLIVE2222

    25 I/O and 2 x analogue gsm controller

    Well if you choice the basic language compiler and knowing that they have good documentation it's should be affordable. You can try before buy by downloading they compiler evaluation version. Here under the GSM example provided on they web site to have an idea. ' * ' * Project name...
  19. OLIVE2222

    Very Small Transformer

    glad to help! indeed Flyback Transformer are smaller but not intended to be connected directly to the main. They are not made with laminated iron but magnetic alloy and are part of a larger circuit (alike the one include in the recom module) and they use higher frequency then 50/60 Hz.
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