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  1. KrisBlueNZ

    To shunt or not to shunt?

    As well as providing a 5V supply instead of a 9V supply, you need to make the connections as shown in the "Wiring connection" diagram on the auction page. Red and black are for positive and negative connections (respectively) to the 5V power source (there is no 470 ohm resistor), and yellow and...
  2. KrisBlueNZ

    Recordings=actions

    You want to be able to record an arbitrary noise, and when the unit hears the same noise, it performs the action? Do you want it to detect that noise on top of any other background noise? (Hint: the correct answer is no, unless you have a LOT of computing power available.) The Clapper that Bob...
  3. KrisBlueNZ

    High Current (60A) High Voltage (60V)

    I don't think you can do it with your relay idea, but the circuit you linked to is a nice idea. What you need to do is (a) detect the current flowing in the circuit, (b) apply some kind of comparison and/or time delay, and (c) break the circuit and keep the switch open until it's reset. The...
  4. KrisBlueNZ

    Help with Small Project Please

    This sounds like a really cool project. For non-American readers like me, the temperature range of 200~225 deg. Fahrenheit is about 93~107 degrees Celsius. I agree with Duke on the use of a DC fan. These are much easier to control. Here's a PWM fan controller that should do it...
  5. KrisBlueNZ

    Phototransistor latch circuit?

    Something exactly like that, yes. According to the Texas Instruments and Fairchild data sheets, less than 0.4 us at 10V or higher supply voltage. If you have a problem with a noisy or modulated light source causing multiple clocking, you can add a capacitor across the phototransistor.
  6. KrisBlueNZ

    Two-coil latching relay arrangement

    Right. I think that circuit is your best option.
  7. KrisBlueNZ

    Laptop Battery 19.9V from 12V 7AH lead acid battery

    :):o:D;):p:cool::rolleyes::mad::eek::confused::( :p Hi, somanshumehta :D :eek: Sounds :confused: like a :cool:cool:cool: project.;) :p:eek:;)Thanks for sharing! :rolleyes: :):o:D;):p:cool::rolleyes::mad::eek::confused::(
  8. KrisBlueNZ

    Capacitor Value issues (simple)

    It looks pretty big. I don't know how big a penny is (and the Wikipedia article doesn't help); perhaps a ruler would have been a more international reference! My guess is it's 12 uF. I thought it might be 1.2 uF with the decimal point not printed properly, but there's no room for one. I guess...
  9. KrisBlueNZ

    Two-coil latching relay arrangement

    Hi Tom! Welcome to the electronics point forums. Thanks for giving a thorough problem description up front. That saves a lot of time. If your "impulse" relays are latching relays (and they sound like the same thing), you can get them with single coils (bipolar drive), dual coils with...
  10. KrisBlueNZ

    Capacitor Value issues (simple)

    Just for diversity of opinion... I doubt that the k means kilo-picofarads; K on capacitors normally means 10% tolerance. I've never seen it used to mean "thousand" on any component marking. Only on some old schematics. In that case, the capacitors would be 12 pF, which is far too small for...
  11. KrisBlueNZ

    Microwave Transformer Isolation

    Nice to see you back again, Ted! You don't visit here often, but when you do, your posts are always very helpful :-)
  12. KrisBlueNZ

    Phototransistor latch circuit?

    Use the 555 as a Schmitt trigger to clean up the signal from your phototransistor, and feed it into a 4017 with its reset input tied to its Q2 output. On every pulse the 4017 will alternate between Q0 high and Q1 high. Use a 12V power supply for maximum speed in the 4017.
  13. KrisBlueNZ

    Mosfet Driver

    The data sheet doesn't have any guidelines, and there's not enough information there to be sure. It will also depend on the switching frequency. My gut feeling is that any duty cycle in the range 2%~98% would probably work; anything in the range 5%~95% would definitely work. Like you, I would...
  14. KrisBlueNZ

    Mosfet Driver

    That data sheet is for the LM5100A and LM5101A. According to the block diagram, there is no connection between the high-side and low-side drivers, so I expect you can use them independently. Remember that the source connection for the high-side MOSFET needs to be switching constantly so that...
  15. KrisBlueNZ

    Design question on microcontroller and TIP122

    A TIP122 will drop about a volt, because it's a Darlington transistor. Therefore you can't use it in your application. A general purpose NPN transistor such as 2N2222 will drop something like 0.3V at 250 mA load current. If you use a MOSFET with a low Rds(on) you do not need to worry about...
  16. KrisBlueNZ

    4 Channel Diversity Controller

    Full schematic OK, here's the full schematic of my suggested design. I'm reposting the first two blocks (the highest RSSI detector and the video switcher) because I've made some small changes to them. The circuit description in my earlier post still applies. Here are the remaining three...
  17. KrisBlueNZ

    Mosfet Driver

    I don't know what part number you're planning to use, and the link goes to a 404 error. But in general, you'll probably have trouble because of the logic inside the driver that's designed to prevent simultaneous activation of the high-side and low-side MOSFET. The driver even enforces a short...
  18. KrisBlueNZ

    Building a circuit

    Yes, but try to rely on the tracks for most of the connections, otherwise you end up with a huge number of wires. Start with the IC. You'll have to cut all the tracks under it. Place the most closely connected components near the IC, using the tracks that come straight from the IC pins. For...
  19. KrisBlueNZ

    4 Channel Diversity Controller

    What video standard are you using?
  20. KrisBlueNZ

    4 Channel Diversity Controller

    OK, I've come up with a few design ideas. In this post I'll cover the two essential parts of the design: the highest RSSI detector and the video signal switcher. The whole circuit is designed to operate from a +12V supply. The video switcher IC needs a regulated voltage so I have used a...
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