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  1. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    The SO-8 package has a 1.27 mm pin pitch. I would use both MOSFETs in the device, in parallel. They will current-share reasonably well. SO-8 devices are heatsinked through their leads. You use large areas of copper, and make sure the leads are properly soldered to them. Not easy to do on a...
  2. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    I couldn't say. None of the component markings are visible in the photo. I guess it uses a logic level MOSFET. It must have an unusual regulator if it can run from up to 90V! Why not order one. Then we'll all know!
  3. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    You're looking mainly at high voltage MOSFETs that are used in switching supplies. Devices rated for 100V or less are much more likely to be specified for low Vgs voltages. One of the devices on your list, FDS6982, is specified at Vgs=4.5V. To get the full data sheet, go to digikey.com, search...
  4. KrisBlueNZ

    Micro-controller controlled Spark plug

    duke37, thanks for the explanation. I checked out the Wikipedia article (as I should have done earlier), but it wasn't of much help. It did mention the ballast resistor, placed in series with the primary and shorted out during cranking. The ballast resistor will affect the waveforms at the coil...
  5. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    OK, here's the design I've come up with. Here's a circuit description. U1A debounces SW1, the RUN/PAUSE pushbutton. Its output goes high while the button is being pressed. This signal clocks U3A which is wired as a toggle flip-flop. It controls whether the circuit counts or not, by...
  6. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    OK, here are the errors I've found so far. I'm working just from your layout drawing, comparing it to my schematic. Your schematic has different component references and at least one componet (QP) has the wrong part number. Many of these errors are probably fixed in your actual stripboard...
  7. KrisBlueNZ

    Micro-controller controlled Spark plug

    A couple of suggestions to add to duke37's advice. When the switching device turns off, there will be a big spike at the collector/drain which will be coupled back into the base through the Miller capacitance (*) in the switching device. Therefore you need a drive that not only pulls high...
  8. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    OK. I'm looking at the layout now. Can you modify your schematic so it shows the actual component values you've used please.
  9. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    Yes, that's the idea. The question you asked was whether you would be "_making_ an AND gate _with_ the 555 and the JK flip-flop". So I answered no. You need to AND the output of the 555 with the JK flip-flop. I'm working on the schematic now. It will take a little while.
  10. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    Thanks Chris for your suggestion. I think the underside looks pretty good, don't you? Well, 3.2V on pin 1 of the TLE2022 is definitely wrong. Did you say you looked at that pin with a scope and it was clean apart from a bit of ripple? Could you check the voltages on pins 1, 2, 3, 4 and 8 with...
  11. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    OK, thanks for the diagram with voltages marked. That's very useful. This may seem like a silly question, but are you testing with the TLE2022 installed? The voltage on TLE2022 pin 1 is neither high nor low, and if the TLE2022 is present, it should be driving that pin either high or low. The...
  12. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    You need the reset button to reset the run/pause flip-flop. Both the D-type and the JK-type flip-flops have Set and Reset inputs. No! You don't need a 555 at all. I'll draw up a schematic. That will save time for both of us.
  13. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    That's a trick question, because you haven't told us how much current the 6V motor draws! Also, you will lose most of your 6V because (a) using the transistor as an emitter follower like that, you will get about 0.8V lost across the base-emitter junction, and (b) when sinking current, the 555's...
  14. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    That circuit is almost right. The negative wire from the power supply needs to be connected to the 0V rail of the circuit, that is, the MOSFET's source. And you need to change the marking on the battery so it only says 12V. Then you can specify the MOSFET part number. I can't suggest any...
  15. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    I don't know how much electrical noise a motor makes. It will depend on the design of the motor, the mechanical load on the motor, the amount of voltage applied to it and the amount of current it draws. You don't have to power the 555 circuit from the same power supply that you feed to the...
  16. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    It's looking pretty good. Re the capacitors that should be changed to ceramics, I was only talking about C1 and C2. C3 needs to be a good quality capacitor because it will be suppressing some high-current noise. A polypropylene capacitor such as the one at...
  17. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    I was talking about logic gates, not JFET gates. You need a logic gate of some kind to generate the MR signal for the tens of seconds counter. It needs to combine your global reset pulse (from the Reset button after debouncing) with the output of the logic gate that detects when bits 1 and 2 of...
  18. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    I don't understand your first question. The pushbutton feeds the debouncer which generates a short pulse (positive, because the 4013 and 4027 are both clocked on the rising edge), which goes into the flip-flop clock. The flip-flop controls the run/pause state of the circuit, so its output gates...
  19. KrisBlueNZ

    Can I return to a return?

    That's a valid point. Not relevant for assembly-language programs where parameters are usually passed and returned in registers and calling conventions are explicitly stated for each function. In high-level-language programs, the only way to chain to a second function at the end of the first...
  20. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    1. The duty cycle potentiometer should be labelled "Pot" or "Potentiometer". "Pot.meter" is not a normal abbreviation and could be confusing. 2. Your potentiometer doesn't need to be a 2W type. A standard potentiometer rated for 1/2W or even less is fine. By convention you only indicate...
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