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  1. KrisBlueNZ

    Is anyone using DesignSpark PCB?

    Any opinions on DesignSpark PCB? It's a free schematic and PCB suite being promoted by RS Components and Allied Electronics. http://www.designspark.com/eng/page/designspark-pcb-home-page
  2. KrisBlueNZ

    6 CELL LI-ION 22.2V BATTERY LEVEL MONITOR

    Most likely there's a mistake in your board layout. Did you draw a diagram of the layout before you built it up? If so, can you post that? Can you also post clear photos of both sides of the board? Disconnect R6 temporarily and work with R4 only. Connect the circuit to a variable power supply...
  3. KrisBlueNZ

    Rewiring 7-band EQ

    You're welcome :-) OK. That looks like a very well-made unit and you've done a good job cleaning it up. I'm still having trouble figuring out how it all fits together. I'll describe what I've figured out so far, and you point out any mistakes, OK? I'm starting with the interconnection diagram...
  4. KrisBlueNZ

    Voltage regulator problem

    Chris, the eBay page says the resistance is 37 ohms, hot or cold. It's in the first paragraph under the pink heading.
  5. KrisBlueNZ

    Need help wiring lights

    Happy growing :-) (I hope you live in Colorado or Washington State!)
  6. KrisBlueNZ

    Need help wiring lights

    Yes. That's the meaning of that specification. Any voltage in that range is acceptable.
  7. KrisBlueNZ

    Voltage or Amplitude?

    Right, and that's a good way to define clipping. Any time the signal hits a voltage limit, the part of the signal that "wants" to go past the limit is chopped off - "clipped". With the circuit that has the emitter connected straight to the 0V rail, the "right" amount of base bias current...
  8. KrisBlueNZ

    Rewiring 7-band EQ

    Right. That diagram is helpful but there's not enough detail for me to be sure of anything. It raises a new issue though: the record player uses valves (tubes). This will probably be a problem because tube circuitry operates at high impedance. This means in simple terms that the signals are...
  9. KrisBlueNZ

    Rewiring 7-band EQ

    Yes, you're right, except that when you measure voltage, you are measuring the voltage that is PRESENT between two points in a circuit, not how much voltage it can "handle". Voltage is measured between two points, by setting the multimeter to a voltage range and connecting the probes to two...
  10. KrisBlueNZ

    Rewiring 7-band EQ

    You need to measure resistance on all those wires. Measuring voltage won't tell you anything. (Measuring resistance probably won't tell you much either.) From the schematic, it looks like four of those wires (brown, grey, white and green, I think - the schematic is blurred) are used for...
  11. KrisBlueNZ

    Camera help. Component ID

    They are surface-mounted inductors. They should have had a value printed on the top - something like "470" or "121". This gives the inductance value in microhenrys, with the first two digits being the first two digits of the value, and the third digit being the number of zeros to add at the end...
  12. KrisBlueNZ

    Please clear my doubts in embedded system

    Generally embedded software is mostly written in a medium-level language like C with assembly language used for specific situations where C is not suitable: 1. If the device is severely resource-constrained (tiny amount of RAM and/or code memory); 2. For sections that need to run as quickly as...
  13. KrisBlueNZ

    6 CELL LI-ION 22.2V BATTERY LEVEL MONITOR

    Great! Thanks for the pic :-)
  14. KrisBlueNZ

    Buying stuff from China.

    Watch out for the Class 2 and 3 multi-layer capacitors! Low-quality ones can have very poor performance. Also, we (at my previous job) had significant trouble with field failures of a particular brand of 0.1 uF MLCCs in a through-hole package. They went extremely leaky (a few hundred ohms...
  15. KrisBlueNZ

    6 CELL LI-ION 22.2V BATTERY LEVEL MONITOR

    Yes you can try two 9V PP3s, or build, buy, or borrow a variable power supply. Actually that circuit will draw most current in the red state, but the difference in current drain between green, orange and red is pretty small. BTW you won't see yellow. Green and red make orange.
  16. KrisBlueNZ

    Need help wiring lights

    Your schematic doesn't show the LEDs connected properly. The top and bottom ones are shorted out. Also, those LED sticks don't contain three LEDs in parallel like that; they contain many LEDs, probably in series, with some drive circuitry as well. I would just draw them as rectangles, marked...
  17. KrisBlueNZ

    Pulse timer module

    Here's a circuit that should do what you want. It contains two identical independent oscillators with independently adjustable ON and OFFperiods (up to about 7 seconds each), driving two relays. It needs a 12V DC supply rated for at least 100 mA to be provided on CN1. CN2 connects to the two...
  18. KrisBlueNZ

    Buying stuff from China.

    Definitely, avoid Chinese adapters. They may use mains wire that's far thinner than it should be, to save copper. I've had one where the insulation was so poor that the outer insulation broke around the plug when moderately bent, and the insulation around the cores flakes off with a little...
  19. KrisBlueNZ

    Voltage or Amplitude?

    Yes, your simulation in post #6 is clipping. Part of the problem is that the transistor isn't biased properly. For the widest output swing without distortion, your transistor should be biased so that when no input signal is present, its collector voltage is about half the supply voltage. In...
  20. KrisBlueNZ

    Delay Circuit

    Actually it first appeared on the author's blog: http://xkcd.com/730/
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