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  1. KrisBlueNZ

    Heyelp! Tapco S5 active monitor problem

    OK, they're all wrong! Pins 1 and 5 should be connected together. I don't know how they can measure different voltages. Could you check that please? Measure resistance between the pins to check that they're connected together, then re-measure the voltages. The negative supply rail seems to be...
  2. KrisBlueNZ

    Help with power supply

    OK. That's just a typical one. It will probably be fine but I can't promise that. Do you know the rated power consumption of the power supply? Is there a sticker somewhere near the AC power socket with a number of watts (W) or volt-amps (VA) marked on it?
  3. KrisBlueNZ

    Help with power supply

    Hi there and welcome to Electronics Point :-) It was probably an NTC (negative temperature coefficient) thermistor, used for inrush current limiting. Something like this: http://www.digikey.com/product-detail/en/MF72-010D13/317-1199-ND/1190974 It's also possible there may be other damage to...
  4. KrisBlueNZ

    H-bridge 12v DC motor

    Once you've decided on a design to use, if you can't get it working, post the following information: 1. The schematic diagram you worked from 2. A list of any changes you've made (component substitutions etc) from that diagram 3. A photo of your construction 4. A list of the voltages you...
  5. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    Hi again. Sorry for the delay! Can you make one more continuity measurement please. Can you check that there's continuity between the two circled points. You can also remove the battery from the voice changer and power it from the amplifier. Don't make any other changes yet to the voice...
  6. KrisBlueNZ

    IR2110 Mosfet Driver Capacitance Question

    Yes, that's right. They are only ever charged when the common of the output MOSFETs is low. At that time they are charged through the diode, to the driver's supply voltage. That's the maximum voltage that should appear across the bootstrap capacitor. When the output switches high, the negative...
  7. KrisBlueNZ

    Timing Circuit? Counter?

    OK, so this is just assisted manual routing. It probably also has a ratsnest mode, where the connections between pins are all shown as thin, straight lines. This can be helpful when you're moving components around, so you can see where the large concentrations of tracks will be, and you can...
  8. KrisBlueNZ

    Timing Circuit? Counter?

    Sure. You will need to find out which end of the PCB component is numbered 1 and which end is numbered 2. Edit: Sorry, that was a reply to a post that was rapidly superseded! Edit2: OrCAD/SDT III is ancient! You won't find it now, except in a computer museum. And on my laptop! I doubt whether...
  9. KrisBlueNZ

    4093 and 4070

    You must connect them (Edit: You must connect ALL INPUTS) to something, otherwise they will float and pick up noise. This can cause increased current consumption (because the MOSFETs inside the gate operate in their "linear region" where both can conduct simultaneously, causing a current path...
  10. KrisBlueNZ

    How to replace old power cord with polarized cord for 1955 Zenith T825

    Hi Tom and welcom to Electronics Point:-) I think you would be better off joining a forum specifically about antique radios. Electronics Point is oriented towards general modern electronics subjects. We do have some more senior people here, but I don't think they're into antique radios. They...
  11. KrisBlueNZ

    Timing Circuit? Counter?

    OK, OrCAD/SDT III's netlist program doesn't know about ExpressPCB (it wouldn't have existed back then) and it also can't do PADS (at least not under that name), but here's its attempt at a Multiwire netlist. Again, remove the .txt extension.
  12. KrisBlueNZ

    Adding buttons to a mouse.

    Everything in a mouse is done inside the chip. If the chip is designed for use in other models of mice that have more buttons, it may have pins that you can connect to extra buttons. But if it doesn't, you don't have any options.
  13. KrisBlueNZ

    Timing Circuit? Counter?

    No worries. I don't use Tango; just their netlist format. My EDA package (OrCAD/SDT III - yes, also very old-school) can generate lots of netlist formats. Give me a list of the formats supported by your PCB program and I'll see whether it can do them.
  14. KrisBlueNZ

    IR2110 Mosfet Driver Capacitance Question

    Hey Fish, That's fair enough. The gate capacitance is only charged and discharged on transitions, so that isn't really a factor, and the gate impedance is infinite. It's really just the continuous load current of the high side driver that will discharge the bootstrap capacitor. The data sheet...
  15. KrisBlueNZ

    sampling communication lines without interfering the signal

    What's the bidirectional level shifter IC you're using?
  16. KrisBlueNZ

    Heyelp! Tapco S5 active monitor problem

    Hi there and welcome to Elecronics Point :-) Most likely the LM3886 will be the fault. These are available from Farnell fairly cheaply - see http://uk.farnell.com/texas-instruments/lm3886t/amp-audio-mute-68w-3886-to-220/dp/9493603 (BTW thanks for putting your location in your profile. It tells...
  17. KrisBlueNZ

    Timing Circuit? Counter?

    OK, here's a netlist giving the connections between the components in the diagram. It's in Tango format and it's readable. Each net starts with an open parenthesis on its own line, then a net name (which is just a number if no name is specifically given in the schematic), then one or more lines...
  18. KrisBlueNZ

    Help with circuit

    1. As Steve said, R5 is far too low. Something like 100 kΩ or 500 kΩ would be better. 2. The schematic does not make it clear whether the wire from pin 2 of the 741 to the wiper of R5 is supposed to connect to the junction of R5 and R6 but it IS supposed to connect there. 3. R3 and R4 are not...
  19. KrisBlueNZ

    IR2110 Mosfet Driver Capacitance Question

    Hi Fish! Nice to see you here again. I agree with Adam. I don't see any reason at all to "balance" the capacitance in the drivers. They're just there to provide the energy needed to charge the output MOSFETs' gates. The driver IC takes care of preventing shoot-through (or it should!) and that's...
  20. KrisBlueNZ

    Timing Circuit? Counter?

    No, there are several steps. It depends how tightly integrated the schematic and layout parts of the software are. If there is enough information in the schematic to specify the package, then the layout part can automatically choose and place the component outlines. A netlist is a list of...
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