Search results

Search Forums New Posts
  1. KrisBlueNZ

    Assembly code for arm

    I don't know. I don't know ARM assembly language. What does the assembler manual say about it? Have you checked my other suggestions?
  2. KrisBlueNZ

    Connecting 12v dc motor to a rc circuit car

    That doesn't necessarily follow. I think you would be best to decide on your requirements then work out how best to meet them. DC motors have an optimum operating point where input power (voltage x current) is most efficiently converted into output power, and you should be aiming for that...
  3. KrisBlueNZ

    switch 2 VGA outputs from laptops to one projector

    Yes, that IS a KVM switch. You just don't use the keyboard and mouse switches. You can make one yourself with a multi-pole rotary switch. You can also use multiplexer ICs. But it's cheapest and simplest to buy one.
  4. KrisBlueNZ

    Hello all

    Hi Kad! Welcome to Electronics Point :-)
  5. KrisBlueNZ

    Assembly code for arm

    Odd that the assembler is reporting a syntax error for line 3, which is blank! Are your directives and instructions indented from the left column? Is "start" a label? Usually these need a colon at the end. (Where they're defined, not where they're referenced.) Find some sample code and...
  6. KrisBlueNZ

    solar charge controller

    The "old" design has a few problems. 1. I would add a resistor in the line that goes to U2 pins 3 and 6 otherwise they could be damaged by excessive voltage when the Dump pushbutton is pressed. 2. Q1 doesn't need to be an IRF540 - a much smaller MOSFET such as BS170 or 2N7000 would be fine...
  7. KrisBlueNZ

    Connecting 12v dc motor to a rc circuit car

    Yes, as Dave says, it's not just the circuit that will need to handle a higher current - you'll need a pretty big battery too. I guess you want to use this receiver with a different car? One with bigger motors and a bigger battery? Those 12 motor driver transistors will not be able to handle...
  8. KrisBlueNZ

    Homemade desk fan

    If you connect a DC fan to an AC source, it will just hum, and not turn. An adapter just puts out a steady voltage. A "charger" as used with a laptop or cellphone does the same thing; the laptop or cellphone takes care of monitoring the battery charging process and stopping when the battery is...
  9. KrisBlueNZ

    Homemade desk fan

    Yes. A "12V" adapter puts out 12V DC unless it specifically says AC. The adapter should be rated for more than 0.07A current though, mainly to give a safety margin. But that won't be hard to find.
  10. KrisBlueNZ

    Trying to create a plug and play set of devices

    Different members of the 1-wire component family can be distinguished because the bottom eight bits of the 64-bit serial number identifies the device type. So you can distinguish between a DS1822 temperature sensor and a DS2408 I/O expander. But if you use the DS2408 on several different types...
  11. KrisBlueNZ

    relay to power a 12v bilge pump

    I don't understand why you would use a light bulb. You've described my circuit, except that you're switching your power to a light bulb instead of the coil of an interposing relay. I don't know why you would do that.
  12. KrisBlueNZ

    Arduino Step Sequencer Help

    Yes it sounds like you could do what you want using a DAC, if the Arduino Uno has one. If it doesn't, you could use an external DAC - these are available with SPI so you only need a few pins to control them. If you want to be able to adjust the voltages in real time, you could feed the trimpots...
  13. KrisBlueNZ

    Trying to create a plug and play set of devices

    I'm not really sure what you're asking for, but if you want a component with a unique ID, have a look at the Dallas/Maxim one-wire devices. They are manufactured with unique identifiers and can be read with a single I/O pin on many micros. Many of them have basic I/O features - the DS1822 is a...
  14. KrisBlueNZ

    0-60VDC POWER SUPPLY CONTROLLED BY 0-5VDC

    Oh, that's even worse! Really? I would have thought both of those things would increase the delay. From what I've seen, this problem is normally handled by adding a fast negative feedback path using a capacitor from the op-amp output to the inverting input, which slows the op-amp down. Another...
  15. KrisBlueNZ

    0-60VDC POWER SUPPLY CONTROLLED BY 0-5VDC

    Steve, wouldn't there be a stability problem with two common emitter stages inside the feedback loop? I don't really understand how to calculate stability but my gut feeling based on prior experience is that the extra gain and delay introduced by even a single common emitter stage inside an...
  16. KrisBlueNZ

    Polarity Protection

    Ah, right. If the load is powered from another source, the MOSFET will conduct and feed that source back into the input power supply. Good point Steve.
  17. KrisBlueNZ

    Polarity Protection

    I don't understand, Steve. The MOSFET won't conduct when the input supply polarity is reversed. What do you mean?
  18. KrisBlueNZ

    relay to power a 12v bilge pump

    Right, you need an "interposing" relay to boost the switching capability of the existing relay in the water detector. You need to use the existing relay contact to complete the circuit from a power source to the coil of the interposing relay. So you connect your positive supply to one contact...
  19. KrisBlueNZ

    Polarity Protection

    Yes I think that will work. This is how I understand it. Yes, I think the diode shown is the internal body diode of the MOSFET. When voltage is applied the right way round, the diode conducts and enables current to flow in the load. It also keeps the MOSFET's source voltage close to the...
  20. KrisBlueNZ

    Designing DC motor with 8051 and transisors

    I have moved your new post to this thread. Please don't start more than one thread on the same topic. Yes you do need the base resistors for the bottom two transistors, yes. The inputs need to swing from 0V to +V and if you don't have the base resistors for the bottom transistors, they will...
Top