Search results

Search Forums New Posts
  1. KrisBlueNZ

    Designing a Time Delayed Relay

    Yes! No. 2 oz should be fine, if you make the high-current traces wide and on both sides. It's better to add the LED in series with the power supply. That will mean it will glow brighter when the relay is ON, which might be a good thing. Here's an updated schematic. I've also shown the...
  2. KrisBlueNZ

    Next/previous switching a multiplexer

    OK, thanks for the information. Yes, disconnect pin 2 of the DIN socket on the receiver. I would say that the component symbol should include pin 3, but that's their decision to omit it. The IC obviously does have a pin 3, and yes it's not connected internally. I connect pin 3 to pin 2 on my...
  3. KrisBlueNZ

    Voltage regulator.. or Help the noob!

    That's a good idea. No, you don't need any protection with a separate SLA battery.
  4. KrisBlueNZ

    Source/sink

    OK. You need to increase the 1k resistance. The hand and the 1k resistance form a voltage divider. The hand's resistance is a lot higher than 1k and this means that most of the 3.3V is lost across the hand, leaving only a small voltage across the 1k resistor to appear on the input pin. Try...
  5. KrisBlueNZ

    Source/sink

    Sinking and sourcing relate to an I/O pin that's used as an output. When it's used as an input, sinking and sourcing are not applicable. When you are driving an analogue input from an external circuit, relatively little current flows into the input. When you connect a +3.3V source to the input...
  6. KrisBlueNZ

    Designing a Time Delayed Relay

    Right. Ground the box if it's made of metal, or use a good thick plastic box. All three of the connectors to the board need to have two conductors, but the current monitoring input and the relay contact output should have many pins per conductor unless you use really big meaty connectors. I...
  7. KrisBlueNZ

    Hello!

    Hi John and welcome to Electronics Point :-) What kinds of electronic circuits are you interested in?
  8. KrisBlueNZ

    How to remove unwanted voltage?

    There is not much detail in your description. If the voltage from the differential amplifier is drifting below +100 mV because of drift in the sensor due to temperature, clamping the voltage to a minimum of +100 mV will not correct for this drift. Clamping the voltage will cause part of the...
  9. KrisBlueNZ

    How to remove unwanted voltage?

    You need to explain your requirements a lot better than that. What does this input come from? What are you using it for? Can you explain the project in general? How much current will be flowing in the circuit? What power supply rail(s) do you have available? Can you provide links to the...
  10. KrisBlueNZ

    Voltage regulator.. or Help the noob!

    I would rather avoid the requirement for him to unplug the regulator from the cigarette lighter before using the car. That's the kind of thing that can be easily forgotten. Well, I do have a desktop machine that dual-boots with MS-DOS, but on my main computer, I use DOSbox 0.74 to runOrCAD/SDT...
  11. KrisBlueNZ

    EEG to tDCS

    Hello SJK, and welcome to Electronics Point. I have temporarily closed your thread while we decide whether to allow discussion of TCDS on Electronics Point. We will let you know when a decision has been made.
  12. KrisBlueNZ

    Need help determining components for a circuit.

    Cool :-)
  13. KrisBlueNZ

    Measuring the time between two electrical pulses.

    I like Harald's idea too. Stopwatches don't normally resolve to better than 1/100th of a second and for such short times, they aren't usually very accurate (I did a big survey of stopwatches and discovered that most of them are pretty badly implemented). The sound card idea is a good one if you...
  14. KrisBlueNZ

    Voltage regulator.. or Help the noob!

    Thanks Dave for answering those questions. Yes my input protection is over-cautious, but automotive "12V" can be a lot higher than 35V during short spikes (due to heavy current flow and inductance) and under a condition called load dump (https://en.wikipedia.org/wiki/Load_dump). It is the...
  15. KrisBlueNZ

    Source/sink

    Hello and welcome to Electronics Point :-) Sourcing and sinking relate to the direction of current flow. When a logic output is high, which is +3.3V in your case, the circuitry inside the device that is driving that output "pulls" the output to the +3.3V supply rail, and the output "sources"...
  16. KrisBlueNZ

    Voltage regulator.. or Help the noob!

    No; I think those switching regulators have ten-turn trimpots and can be adjusted pretty accurately. Right. I meant to mention this before. A standard DC motor will not give a stable rotation speed. You would be much better off using a stepper motor, or a brushless motor, whose speed can be...
  17. KrisBlueNZ

    Capturing system block diagrams

    For block diagrams, and other diagrams in general, you might want to consider Visio.
  18. KrisBlueNZ

    Designing a Time Delayed Relay

    Right. The 110VAC input can be a small connector, but the other two should be rated for at least 30A. Also, ideally, they should be different from each other, to avoid confusion. Whether you use connectors with two very large contacts, or connectors with multiple smaller contacts, is up to you...
  19. KrisBlueNZ

    Power Supply Diagram

    Hello and welcome to Electronics Point :) 1. You need to connect the negative side of the bridge (on the left) to the 0V rail. It looks like you just forgot to join the line up. Edit: Oh, you already said that. 2. You need a smoothing capacitor as well as the 0.1 µF decoupling capacitor from...
  20. KrisBlueNZ

    Camera strobe light

    There's no such thing as a "continuous flashing" light. How many times per second do you want it to flash? Xenon flash tubes, like the ones used in cameras, operate from a large capacitor that stores a lot of charge. In a camera, the capacitor is charged by a little oscillator (the thing that...
Top