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  1. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    No, they're used as voltage droppers. A forward-biased silicon diode drops about 0.6~0.8V depending on the current flowing through it. Three of them adds up to about 2V. So with a 3.3V/0V swing at the circuit input, the gate of the top MOSFET swing will be about 5.3V/2V. The MOSFET sees a...
  2. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    I understand but that's wrong. On every multiplex phase, you need to clock a full set of new data into the cathode drivers. The only exception would be if every slice was displaying an identical pattern. Remember with multiplexing that you have to drive each slice in sequence, in a loop. On...
  3. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    WARNING! THIS CIRCUIT HAS SEVERAL PROBLEMS AND I DON'T RECOMMEND IT! Here's a way to drive a P-channel MOSFET that will switch it very quickly and cleanly. Q3 is the main P-channel MOSFET. I've shown it as half of a DMP2035UTS dual P-channel device, which has good specifications (35 milliohms...
  4. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    OK, so you have eight "slices", each containing 8x8 RGB LEDs, and the anodes of all 64 LEDs in one slice are commoned and driven by one of eight MOSFETs. So each slice has 192 cathodes, right? And you will be driving these using twelve 16-channel driver ICs? As far as persistence of vision is...
  5. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    I see what you mean. In that case yes he will need eight anode drivers.
  6. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    Let me get this straight. You're making a cube. Each face is covered by a grid of 8x8 RGB LEDs, common anode type. A cube has six faces so the whole project could be described as a 6x8x8x3 cube? You want to multiplex the cube in six phases, one for each face. Each face has 64 LEDs, each with...
  7. KrisBlueNZ

    interfacing 3.6v flash memory to PIC microcontroller

    That NXP app note you cite, and the one Steve linked to, relate to I2C communication. I2C is a multi-drop bus and needs special handling to get multi-drop behaviour across different supply voltages. You said your Flash EEPROM is SPI; you don't need any special handling here, since all signals...
  8. KrisBlueNZ

    6 Buzzer Project

    OK. You said you thought this could be done with relays. Here's one way to do it with relays, lots of diodes, and a few small components. No active semiconductors. I've posted this design to show that it's possible, but it may not be practical, depending on your requirements, because of the...
  9. KrisBlueNZ

    Rom circuit

    No! Not here. That's not the purpose of these forums. You can come here with specific questions, and find someone who has the relevant experience and can advise you. If you want to learn electronics in general, search for electronics tutorials. There are lots around on the web. If you want a...
  10. KrisBlueNZ

    Rasberry Pi + Relay

    There's not much detail on the Sainsmart web page. I hope they would include a sheet with the unit, to explain how to connect it up. The page says that the board requires a power supply of 5V and draws up to 160 mA. Is this available from the Pi? The control inputs on the board are specified...
  11. KrisBlueNZ

    Amplifier power supply capacitor removal advice needed!

    OK, cool
  12. KrisBlueNZ

    Relay? help?

    Interesting and helpful advice Steve.
  13. KrisBlueNZ

    Wanted$$: Super simple 8 input & 8 output select

    Thank you very much Bob. I respect your opinion and that comment means a lot to me. I was also hoping that this project could be a learning exercise for everyone here. If it goes ahead with me, I hope I'll be able to post progress updates here, and include some information about the design. I...
  14. KrisBlueNZ

    Relay? help?

    I've taken the liberty of designing a circuit for you! I guess it must be a slow night ;-) I've shown two versions. The first one uses high-current MOSFETs to switch the lamps, and the second one uses a grunty relay. The second one is simpler and probably more reliable, but it will make an...
  15. KrisBlueNZ

    Wanted$$: Super simple 8 input & 8 output select

    Steve and Bob have actually been trying to help you by telling you why you are not getting a good response here. You have repeatedly told us that this is a legitimate business enquiry, but our uncertainty about the genuineness of your offer is not your stumbling block. You need to know, then be...
  16. KrisBlueNZ

    Wanted$$: Super simple 8 input & 8 output select

    OK, enough bullshit. I offer to do this job for USD 500. Here are my conditions. 1. You will first provide a thorough detailed description of the application for this circuit, including all human factors (you mentioned "fidgety fingers"), any timing requirements, startup behaviour, and details...
  17. KrisBlueNZ

    automatic switch

    Aj_s87 there is an elephant in the room on this thread, and it is the device you want to power. What is it? Do you have a manufacturer and model number? A link to a sales description? A schematic diagram? A detailed description?
  18. KrisBlueNZ

    Amplifier power supply capacitor removal advice needed!

    Those are 620k (kilohms), i.e. 620,000 ohms, not 620 ohms. Apart from that, they should be suitable.
  19. KrisBlueNZ

    automatic switch

    Agreed Steve. I had a think about this one too, and came to a similar conclusion. Other difficulties are the fact that the dynamo is a magneto and just produces bursts of voltage, that these bursts could peak at very high voltages and could include noise and spikes, and that the load...
  20. KrisBlueNZ

    Wanted$$: Super simple 8 input & 8 output select

    Try freelancer.com. Lots of people there seem to be prepared to be messed around for the sake of a few bucks. Some of them are probably competent, too :-)
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