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  1. K

    Artifact-less ISM band radio transmitter part

    I have tried a couple of FSK/OOK wide frequency range transmitters (among the lines of 100 - 1000 MHz) at 433.92 MHz. They both produce artifacts; i.e. extraneous signals in front and / or after the desired signal - in either OOK or FSK modes. I am sure there are some parts out there that are...
  2. K

    Heater thermsotat receiver unit

    Ah, hijo del diablo! I was installing it the wrong way: 230V mains on relay output and heater RT-in on the thermostat input :oops: So, now with the new polyester cap fitted and correct wiring, it still behaves the same. I.e. "my central heating would not start / stop every time the transmitter...
  3. K

    Heater thermsotat receiver unit

    Err, bad pictures again i think. It is not melted, it looks just as in that pic that Tha has posted earlier. And anyway, even without that inductor - same deal when i have put the receiver back into its place
  4. K

    Heater thermsotat receiver unit

    Upon closer examination and @Tha fios agaibh's picture above it turns out the variable inductor is OK; it was just bad lighting making me think it has melted. Also, the tall cap as well as every other caps are OK, and no shorts on diodes or other 3 legged semiconductors. I guess I need to dig...
  5. K

    Heater thermsotat receiver unit

    Here it is. Sorry for the bad photo; The red screwed thing is not marked in any way (or not any more). Any chance I can find out what it initially was ?
  6. K

    Heater thermsotat receiver unit

    Sorry, they are both on the right side, big, rectangular; only their corners sticking out in the photos. That is neither corrosion nor wax. The little red thingie with a screw on top, I believe it is its plastic casing melted down :D. Let me grab a photo of it from its side. And yes to the film...
  7. K

    Heater thermsotat receiver unit

    Hello, my central heating would not start / stop every time the transmitter thermostat would issue a start / stop command, but only some of the time. Took the receiver apart, found the film cap (yellow) next to the output relay to be off by a big factor (200 nF measured / 560 nF nominal) and...
  8. K

    Have I killed the MCU for good ?

    by, maybe, grounding a HIGH output ? I have a PCB with an Atmega88PA MCU and an ADS114S06 ADC that both share three SPI lines (SCK, MISO, MOSI). I was trying to program the MCU (via SPI interface), it responded with its device signature OK, but then verifying the flashed program would fail on...
  9. K

    weird DMM voltage readings

    R1 is 270 ohm, and as I have said, taken out of its PCB - together with L1 and a 3.2 V battery it does light up. No shorts there, no wrong measure points, no bad PCB traces. It might be a wrong hex file for the MCU model, I don't know. But that's just the context, the real question is why...
  10. K

    weird DMM voltage readings

    The MCU is an ATmega88 set to sink current, nothing out of the ordinary about it that I can think of. The pin is PB6 and I have also tried sinking into PC1 (another pin) - did not take readings on that one but the LED remained off. Anothert thing I have attmepted was to connect 2 xAA batteries...
  11. K

    weird DMM voltage readings

    Hello, I am trying to debug some PCB - the LED below won't light up Took ut my trusty DMM and measured V_AC = 3.31 V V_BC = 1.33 V V_AB = 0 V <--- ?? should it not be around 2 V ? Thanks!
  12. K

    Using this magnetic sensor as a wakeup sensor

    @Alec_t it is the 1022. Good idea @(*steve*) however, thinking more about it I don't think I should be using it anyway since it needs to operate around 10 seconds per minute. But out of curiosity, how would I make it work 100ms / sec ? With some combo of a 555 and a transistor maybe ?
  13. K

    Using this magnetic sensor as a wakeup sensor

    I have overlooked that aspect... Yes, I need to sense a couple of uT; there are alternatives but only in minute packages with no leads. Extremely hard to hard to hand solder. One thing I do not understand, the 4 resisors of that Wheatstone bridge are 1.1k each. Should the drain not be more...
  14. K

    Using this magnetic sensor as a wakeup sensor

    for the rest of the circuit. Here is the sensor's datasheet However, looking at the diagram of interest makes me think this is going to drain the batteries quite fast due to that LMV324N comparator and its voltage divider on the positive terminal. Is there any way to tweak this design for...
  15. K

    in-car (passenger) electronic device use: resonance vibration natural frequency

    You have got a point there; if it rolls over -> not good. And since the enclosure won't be mounted in any way.. I guess I'll take the standard route with epoxy staking and screw mounting (PCB <-> enclosure). My biggest part is going to be a finger press button. And maybe a bent led. I am...
  16. K

    in-car (passenger) electronic device use: resonance vibration natural frequency

    Hi, I have this smallish gadget that I want to use inside my diesel engine car. It is mostly going to sit somewhere inside the car for the most part, and I am considering vibrations. The PCB is under 100 g / 4 oz and about 45 x 50 mm / 1.8 x 2 in. From what I read this makes for a low mass...
  17. K

    Regular power in fries it, SPI power in sails it

    Yep, camera's dead :| Hope these are fine. The red fat cap is C1 on upper left side.
  18. K

    Regular power in fries it, SPI power in sails it

    Eh...reversed the voltage regulator and fed it 9.7 V through the multimeter - again got back that 0.1 mA reading (and a non-functional circuit). Took out the part and replaced it with a new one thinking it might have got damaged during the previous tests. Same deal. Switching the multimeter...
  19. K

    Regular power in fries it, SPI power in sails it

    FML... I am puting it the other way now :P
  20. K

    Regular power in fries it, SPI power in sails it

    Rgiht! - fed with 5.1V - measured 14 mA max - fed wtih 9.7V - measured 0.01 mA - maybe the multimeter sensed danger and limited the current ? It can be seen here how the fat reddish cap's left foot goes into the voltage regulator through a wide trace. I am feeding the PCB through that fat cap...
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