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  1. yesway

    Is there more to engineering than this.?

    After spending a well worth late night hour I wish to thank everyone for a well balanced mix of experience! I dont have much to contribute with here, except a thought that struck me. Some 5 or 10 years ago this discussion would never has taken place about the exclusive and desirable work as...
  2. yesway

    adjustable oscillator circuit

    Hi! I would like to start by saying you will probably have no problem finding an electronic design that will suit your needs, even in full manufacturing. I sense that you have more information that you wish to keep for yourself at this point, and I really think you should. I still have no...
  3. yesway

    Air flow measurement

    Hi folks! Thanks a lot for your advice, maybe I can send you a respirator sometime to thank you :) Well, we arent really building respirators, but rather accessories. For the pressure we need to know + and -, but for flow we have got a "wish" from customer to handle an air volume which...
  4. yesway

    Air flow measurement

    Okay, should have mentioned that we wish to keep power consumption minimal (battery operation). Perhaps this is still possible in some way? Could you please give more details, like expected power consumption, or if other methods are better under these circumstances?
  5. yesway

    Reliability of Ceramic Capacitors

    Okay, then it sounds strange. There must be something really wrong to break the caps in such a configuration. Can you test if the same results occur if there is no cable attached/no signal driven? Sounds quite likely that the cable loads the driver in such a way that the cap sees lots of HF energy.
  6. yesway

    Test Equipment

    I agree with cbarn, much money for little use. I think U should go far with a DMM, an oscilloscope and maybe a milliohm meter for shorts (yes, quite useful). Of course a current limited power supply.
  7. yesway

    adjustable oscillator circuit

    Hi! Moving a magnet back and forth should be no problem, it is basically a tuned circuit, where you would measure the current induced by the moving magnet to get resonance, but it is likely that there are more efficient solutions for a prototype, why not use the magnet+slider from an electric...
  8. yesway

    Reliability of Ceramic Capacitors

    Basically the failure rate is, as stated on manufacturers sites, very low. Much less than 1 in a thousand should show failure during say a few years, if operated at suitable conditions. Many things may shorten life, primarly temperature. Increasing the temp 10'C can decrease life time by 50%...
  9. yesway

    555 timer or VCO

    There are many possible solutions to this! As always performance and price matters greatly. Some thoughts: Being a microcontroller fanatic I would have used a cheap micro if I needed accuracy and well defined rise times, and get some "intelligence" for free, like startup properties...
  10. yesway

    Air flow measurement

    Hi! For a medical (not life supporting) device we need to measure air pressure and air flow. The device must be low cost. We have found a few pressure sensors which have proved suitable (in the 1-2USD range) for the pressure measurements. We are still investigating a simple and reliable...
  11. yesway

    Relay Switching - generating Noise

    Hi guys, just wanted to check how the MCU drives the relay(s)? If it drives them directly (doesnt sound likely in this case?) or via a bipolar transistor it may use enough current from the probably weak zenervoltage for VCC to drop? In such a case you may consider: 0. If possible increase...
  12. yesway

    Passive notch filter needed

    Hi Lewish! The filter is intended to go in the signal path between a cell phone and a small speaker amp, so the signal is about 50-100mVrms, the source impedance is low (10 ohms?), and the load impedance is high (a volume pot of about 10kohms).
  13. yesway

    Passive notch filter needed

    Hi! Would be helped by finding a simple (RC based) filter to blank out 600Hz (and later possibly add notches for 1kHz and 1k2Hz) in a design. At this point I have my eyes on tiwn t's or bridged t's, but would like some expertise of what would suit the situation best, I am sure there are other...
  14. yesway

    SMT compression connector .050 pitch - Who makes em'?

    Hi Winkler! You probably know of JST already, anyways they make lots of connectors, may be worth checking if not already done: www.jst.com best regards
  15. yesway

    Strange resonance phenomenon?

    Hi, sorry for the not-so-descriptive headline, here is the long specification of the problem: In a car kit handsfree set, there is a 2" speaker and a standard microphone. Both are connected via some circuitry to a cell phone. The whole thingy is housed in a small plastic box, which also...
  16. yesway

    GSM interference decoupling

    Thanks guys, Melone in special. I tried out a quite different layout with lots and lots of groundplane and vias to tie both layers together, and voila, instant noodles. Well, the result wasnt perfect, but when does that happen? It was a major improvement for sure. To cbarn24050: gsm in this...
  17. yesway

    GSM interference decoupling

    We are designing low cost handsfree units for car use and have problems with the infamous gsm interference. The PCB contains simple mic and speaker amps and both pick up quite a good deal of 214Hz hum. Any good general rules would be greatly appreciated. We have tried a lot of basic things like...

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