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Recent content by neillsun

  1. N

    Crodnet KXPS5 accelerometer datasheet

    I have two of these breakout boards built by Crodnet. Unfortunately their site is no longer, and I've lost the datasheet. Anyone still have it? The boards I have are white- there is a data sheet floating around for a black breakout board, but my layout is different, and I have 3 jumpers that...
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    [SOLVED] ULN2803 and PWM problem

    SUCCESS!! Ha! Thanks Brian. I reduced the value of the 47k pullup resistor (NPN collector to +24V) to 520R ... the 47k didn't allow the voltage to FET Gate to be high enough to switch the FET off. (Sound like I know what I'm talking about, huh??) Anyway, my test circuit works now. Thank you...
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    [SOLVED] ULN2803 and PWM problem

    Thank you very much. I will try this tomorrow. (I didn't add the pull up to P$19 on this schematic, but I did add it to my (hand drawn) stripboard layout. N.
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    [SOLVED] ULN2803 and PWM problem

    Hi Brian, Thanks for the explanation. I think I am getting my head around it now. I have added the transistor to the schematic - if you wouldn't mind casting your eye over it. Thanks, Neill.
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    [SOLVED] ULN2803 and PWM problem

    I'll have another bash at it this evening and will submit a schematic. Thank you for the help so far! N.
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    [SOLVED] ULN2803 and PWM problem

    Hi Brian, Thanks, I had thought of a second transistor, but didn't think it necessary as the FET I am using is a logic level, so only requires 5V at the gate. Maybe I have something else wrong, but I am not seeing it. N.
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    [SOLVED] ULN2803 and PWM problem

    I'm missing something, aren't I?? I've connected the p-Channel MOSFET (FQP27P06) as follows: Pin 1 (Gate) connected to MCU pin B.3 (PWM pin) with 1M pull-down resistor. Pin 2 (Drain) connected to LED cathodes and Pin 3 (Source) connected to +24V. The LEDs turn on at full brightness, no matter...
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    [SOLVED] ULN2803 and PWM problem

    I'm waiting for the logic level P-channel MOSFET I ordered to handle the high side switching. I'm planning on adding a 100K/1M (?) pull-down resistor to the gate to stop it floating. I'll leave the ULN in place for now. no point in building an array if I don't need to.
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    [SOLVED] ULN2803 and PWM problem

    Thank you both. I'll give the transistor array and switching high side a try. I'll let you know how it turns out. N.
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    [SOLVED] ULN2803 and PWM problem

    Thanks Brian. For the sake of experimentation - and to quell my own curiosity - I think I'll try the transistor array either way. I realise I wasn't particularly clear with my PWM explanation - this is handled by the PICAXE on pin B.3, with the remaining 7 PortB pins as outputs for the LEDs...
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    [SOLVED] ULN2803 and PWM problem

    I am busy building the following: https://www.instructables.com/id/A-sunrise-and-sunset-lamp-with-LEDs/?ALLSTEPS. I appear to have a problem driving the ULN2803A with the PWM controlled FET (IRF520)... or with the ULN2803A being driven by a PWM controlled FET... I currently have 7 LEDs wired...
  12. N

    4x4 matrix keypad with 16f690

    Thanks, Mike, although it still doesn't work! This one has me a bit stumped.
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    4x4 matrix keypad with 16f690

    I am pulling my hair out with this one... I have a 4x4 matrix ketpad connected to pins RC0 thru RC7 (RC0-RC3 are columns and RC4 thru RC7 are rows). I have connected RC4-7 to ground through 10k resistors, and I am using the following code (PICCLite in MPLAB IDE) which I got from...
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    multiple processes on PIC 16f690

    I need to run two 5 digit 7-segment LED displays off a 16f690, which will display a number entered on a matrix keypad. What I am not sure about is how to keep the display lit while data entry is taking place. If I have my display methodology correct, I will have 17 outputs to drive the display...
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    PICKit 2 16F690 programming

    16f690 resets Thanks, BlackOps. I have had a look at Mike Stracey's site before. (and book marked it for reference!). I know that ASM isn't that hard once you know the structure... but I would feel more comfortable with C. Crikey... I know I read something about the different banks, guess I...
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