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  1. KrisBlueNZ

    Adding aux input to Sony PMC-202 stereo system

    OK, the best place to insert your line input is between the input selector, IC309, and the preamp, IC304. Specifically, between R141 and C126 (left channel) and between R241 and C226 (right channel). Here is my suggested modification. I've assumed you want to use a stereo jack socket with...
  2. KrisBlueNZ

    EMITTER DETECTOR SENSOR

    If your output board is "EM222 Relay Output" then the relay outputs are "dry contact". That means they are like a fully isolated switch. You can connect them to any voltage you want; you can even use them to switch AC mains voltage. They are only "24V" outputs if you connect one side of each...
  3. KrisBlueNZ

    Adding aux input to Sony PMC-202 stereo system

    If you want to add an auxiliary input, the sensible place to connect it is at the top end of the volume control. (Or at the input to the tone control section, if that comes before the volume control.) If you have the service manual, you should be able to figure out where to intercept the signal...
  4. KrisBlueNZ

    EMITTER DETECTOR SENSOR

    LOL :-) That makes sense now! So the PLC already has isolated relay contacts for its outputs. You can connect them directly to your 5V motor control circuit.
  5. KrisBlueNZ

    Switch Project Help

    You could use an Arduino but I don't know whether they would meet your low power requirement. They aren't designed for that. The Arduino boards have other parts as well as the microcontroller - specifically, a regulator. I was thinking of a single microcontroller without the support circuitry...
  6. KrisBlueNZ

    How to create a HEX file for 8085 processor along with 2732A eprom

    If you have a listing file that includes the output data, but not a binary image or a hex file, you can create a binary or hex file by copying and pasting the output data together (and for a hex file, calculating line checksums). A few lines from a typical assembler listing could be something...
  7. "notsohot" project - mains power cycler for heating appliances

    "notsohot" project - mains power cycler for heating appliances

    My "notsohot" project will enable a heating device to be cycled on and off with a duty cycle adjustable from <5% to >95%, and a cycle time of around 7 seconds, to reduce the appliance's average heat output (and power consumption). It interrupts the mains supply to the appliance using a triac...
  8. KrisBlueNZ

    "notsohot" project - mains power cycler for heating appliances

    KrisBlueNZ submitted a new Showcase Item: "notsohot" project - mains power cycler for heating appliances Read more about this showcase item here...
  9. KrisBlueNZ

    EMITTER DETECTOR SENSOR

    Sorry Colin. I misunderstood your comment. Yes. You don't need relays at all. But you will need some way to boost the current from each phototransistor. It might be as simple as a second transistor. That circuit connects to the 24V field supply from the PLC and provides a signal to a PLC...
  10. KrisBlueNZ

    Switch Project Help

    Hi there and welcome to Electronics Point :-) Re solar powering, it's surprising how little power you actually get from a small solar panel. If you can tell us (a) the maximum area available for a solar panel and (b) the duration and intensity of illumination between uses of the box (e.g. eight...
  11. KrisBlueNZ

    EMITTER DETECTOR SENSOR

    Oh, so they are! I don't really know what Colin meant by his comment.
  12. KrisBlueNZ

    EMITTER DETECTOR SENSOR

    And the coil resistance (or coil power or coil current, from which the other numbers can be calculated), the contact types and ratings, etc...
  13. KrisBlueNZ

    Connecting Li-ion cells in series

    Does anyone else have any good reason for not paralleling two or more identical cells?
  14. KrisBlueNZ

    Can I drive a P-channel MOSFET from a 74HC138?

    That circuit you linked to uses a P-channel MOSFET, connected between the positive supply rail and the anode of the LED (via a current limiting resistor). When the driving circuit pulls the MOSFET's gate low, the MOSFET turns ON, and becomes a short circuit from source to drain. In other words...
  15. KrisBlueNZ

    Connecting Li-ion cells in series

    Yes, that's right... charge balancing is needed... when the cells are in series! I'm not saying you're wrong about connecting cells in parallel. I don't know. I'm just saying that I don't find that a very convincing explanation. That could be a valid reason. Is there a really good reason why...
  16. KrisBlueNZ

    lm317 sub?

    Right. The CAT-102 that I suggested in post #23 requires a separate power supply connection, and the voltage must not exceed 18V. But it hardly draws any current from that pin, so a simple zener shunt regulator will be fine. Any voltage from 2.2~18V will do; 12V for example.
  17. KrisBlueNZ

    Transistor As Switch Variation

    No. For many reasons.
  18. KrisBlueNZ

    3-5 watt audio amp

    Better give that one a miss. It's obsolete. The data sheet says that at 9V the output power will be at least 3.2W and typically 4W into an 8Ω load at 10% distortion. But that really means that the supply voltage must be 9V. As I said before, and Dave repeated, a little 9V battery is not up to...
  19. KrisBlueNZ

    Help! Someone please help me out on this project

    OK, you need to design a common emitter audio amplifier? Can you retype the information in those images and do the necessary calculations that use your student ID. That would be a good place to start. Then we can see what you need to do.
  20. KrisBlueNZ

    EMITTER DETECTOR SENSOR

    It sounds like the phototransistors are not conducting enough. You said you measured the coil current at 0.04 mA. If your relay is an Electrocomp NT73-2 C S 10 DC5V 0.45 then it has a coil resistance of about 56Ω and will draw 90 mA when fully energised! The phototransistor may not be able to...
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