Search results

Search Forums New Posts
  1. Arouse1973

    zener circuit

    Looking at the data sheet the lowest current for 3.3 V out is 1 mA. Your circuit at 25.8 volts will give 3.69 Volts to the zener. With a BZV55C3V3 I got 2.77 Volts out. Changing the 120K to 5K I got 3.28 Volts out. So I think you are going to need to increase the current a bit to get 3.3 Volts...
  2. Arouse1973

    12 V battery charger from 75V solar panel

    Are you sure it's not 75 Watt at 12 Volts. That's a common solar panel wattage. And the common nominal voltage is 12 Volts but will rise to about 17 Volts in full sun. So do you have one 12 Volt panel or 6 in series? Which would give you more than 70 Volts. Or is it something else, one massive...
  3. Arouse1973

    Chicken Coop Door Opener

    Hi Kris The most common issue I see with EMI events is low current fast switching problems which are down to capacitive coupling between PCB traces and cables. As the fast rising edge from aggressor signal couples to the victim due to capacitance which is the dominant mechanism in low power...
  4. Arouse1973

    Chicken Coop Door Opener

    Found something in the Art of Electronics that explains what I mean. TTL chips (and their HC and AC counterparts)tend to be designed with active LOW control inputs; for instance, flip-flops generally have SET and RESET inputs that are enabled when LOW. External digital signals used as inputs...
  5. Arouse1973

    Chicken Coop Door Opener

    A lecturer of mine who used to work for IBM once told me that about the chip select and reset lines. But I will have a dig about and see if I can find something. Unfortunately I don't have a reference for everything I know, whether right or wrong. :) It makes perfect sense to me about the...
  6. Arouse1973

    Chicken Coop Door Opener

    Hey Kris, there is a good technical reason for using active low and that is false triggering. An EMI event is more likely to induce a positive spike than a negative spike. This is the reason that reset lines and chip select lines are active low. I know it can be factored out in software but you...
  7. Arouse1973

    Chicken Coop Door Opener

    Dan that looks very good well done. One question, when it is dark you are only going to get half supply max on the port pin, is this ok? I guess your using the A to D? I can't really comment on the code, I'll leave that for Kris. One other thing I noticed is the switch is a low to high active...
  8. Arouse1973

    Chicken Coop Door Opener

    I was just going to say I forgot Hysteresis I thought about it but then forgot. Good point about the switches though. :) Adam
  9. Arouse1973

    Hello from S. Ohio

    See you soon :)
  10. Arouse1973

    Chicken Coop Door Opener

    Hi Dan Looks good. Couple of things. 1) What's the purpose of the second mono stable? is it to open the door again when it's light enough in the morning? I am guessing the controller for the door takes a signal of the same polarity for both close and open. See it once for close and see it again...
  11. Arouse1973

    Power for Multiple DC Motors

    Hello You need to make sure your battery can supply that much current. It could be that the AA battery can't supply enough current to run 4 motors, obviously dependant on motor specification. What battery are you using is it NICD or NiMH or supermarket own Alkaline? Also what's the spec of the...
  12. Arouse1973

    Monitor Viewsonic Optiquest Q19WB

    Yes I had a quick look and yes the capacitors seem to be a culprit for some of them. Other than checking for damaged or blown components it's going to mean getting a schematic diagram of the circuit and fault finding from there. This is not going to be easy unless you have done this sort of...
  13. Arouse1973

    My MCU circuit can't start by itself

    A couple of other things to try. A parallel resistor of 1M across the crystal induces more noise which helps the oscillator to start. Sometimes you need to have slightly different value capacitors to get it to start and as Harald mentioned this is what the scope probe is doing. But it could be...
  14. Arouse1973

    Hello from S. Ohio

    Hello Burnmeup. That's the spirit, who cares if your wrong, I get things wrong all the time and I am still learning everyday after doing this for 20 years. There is a good bunch of guys on here with lots of different areas of expertise. And off course there is Ian the admin god, he's actually a...
  15. Arouse1973

    RC-filter for electret mic and USB sound card

    Ok cheers Kris :)
  16. Arouse1973

    RC-filter for electret mic and USB sound card

    A large inductance like that, probably not a good idea on the input of an audio amp that could pickup external magnetic or electric fields. This might interfere with the circuits operation and effect sound quality. Why can't he just do this? C1 and R2 form a high pass filter. With that said...
  17. Arouse1973

    Battery Voltage Drop

    Hi Sadlercomfort Sulphation always happens in lead acid batteries but is normally reversed by fully charging. So if you have not charged the battery for a while or it never gets a full charge between uses then it's sulphated for sure. Whether it can come back depends on how long it's been...
  18. Arouse1973

    Monitor Viewsonic Optiquest Q19WB

    Sounds like a power supply issue. May want to check the capacitors. I have seen lots of underated capacitors on monitors power supplies. Adam
  19. Arouse1973

    Designing an iPhone speaker dock.

    The one I am looking at has one but hey if it has two great this will give you Stereo. Adam
  20. Arouse1973

    Designing an iPhone speaker dock.

    I guess you want Stereo so you need to build two circuits. I have used the LM380 and had good results, you need two for stereo though. Adam
View older results
Top