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Type: Posts; User: Tim

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    Re: Push or pull on fan

    Ewww, metal fan :blue:
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    Re: Push or pull on fan

    Ok I had another go. I think now I'm seeing the effect of the airflow out of the fan in local, not local effects.

    When you have the fan side out, the air flow is pushed around the motor and you...
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    Push or pull on fan

    Hi, sorry this is OT but would appreciate any input.

    I have a project that involves a PC radiator and fans. The current arrangement is with the fan sucking the air through the rad. This means...
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    Re: Simple cheap dev board needed

    I made the purchase of the firewing board as I have some shields etc for it.
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    Re: Simple cheap dev board needed

    Hi

    I in the past was able to disable signed driver requirement and load in the driver. Looking at my laptop I remember now I got it working that way.
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    Re: Simple cheap dev board needed

    Thanks Bob

    Bugger! :(
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    Re: Simple cheap dev board needed

    Hi Bob

    Price up to say 18 idelay with an easy to add LCD with buttons

    The Amicus boards are ~25 and I cannot make them work with USB bootloader on my Win 10 machines. I wasted days on them...
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    Simple cheap dev board needed

    Hi,

    I'm looking for a simple Pic board that I can program to do simple tasks.

    The first one is a flow calibrator. i.e just to connect to a optical sensor and have a display and a couple of...
  9. Re: Getting old, need help on suitability ttl vers RS232

    Hi Ricardo

    Yes I use Modbus but as a slave, I posted the code I think for a fully auto version. I will need to write some more to act as a master. Eg add a timer.

    Actually I will use a hybrid...
  10. Re: Getting old, need help on suitability ttl vers RS232

    Hi,

    It's not half duplex. I will need to send commands to the board for stop start, calibration data etc.

    Tim
  11. Re: Getting old, need help on suitability ttl vers RS232

    I have done EMC testing and the enclosure is more at risk than a shielded cable. I have a lot of fan grill vents that will leak like a sieve in and out.

    The advantage of 485 is the differential...
  12. Re: Getting old, need help on suitability ttl vers RS232

    Hi Rick

    As I said I have installed a buffer. I'm using the SN74LVC2G240 that has ESD Protection Exceeds JESD 22 eg I could probably find a device that has higher standard input v but its not...
  13. Re: Getting old, need help on suitability ttl vers RS232

    Gamboa

    The cable will be shielded, the coms low speed and the info just packets of data that can be resent if corrupted.

    Tim
  14. Re: Getting old, need help on suitability ttl vers RS232

    Thanks every one.

    I have following the help decided to keep it TTL at 5V, The concession I have made though is to add a buffer chip just to help protect the pic. I will add a CRC as well.

    ...
  15. Getting old, need help on suitability ttl vers RS232

    Hello

    TTL vers RS232

    Basics of application

    I have a remote Pic that will be a the end of a cable no more than 3mts away. In fact it will only ever be 3mts.
    The Pic needs to talk to the...
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    Re: Persistence freq for Led Bargraph

    So you have some more context

    This the device I will be driving https://www.ebay.co.uk/itm/121729022958 Its the Green yellow red device

    Now I have written 8 seg LED driver routines but they...
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    Re: Persistence freq for Led Bargraph

    Thanks everyone. I was excited about the PCA8574 but it seems to be 8 bit only and I need 10 bit. However there are other devices like the TCA9555DBR

    So I'm going to check that out.

    Tim
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    Persistence freq for Led Bargraph

    Hello!

    I'm looking to implement a 10 seg bar graph. Now I could wire up all leds to a pic or drivers. Or I could use a 4017 chip and shift the data through it.

    The issue is what freq will I...
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    Re: Cread on 14 bit core

    What I would consider is that you write a retlw $55 at the end of the code space in your code. Make the call but before make a note of say tmr0. If the Tmr0 value is not as expected for a read then...
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    Re: Cread on 14 bit core

    Arrr

    I understand now....
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    Re: Cread on 14 bit core

    Cread reads a memory address, If you read back $FF then its pretty certain it was not written to yet. Unless you wanted $FF there..
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    Re: H bridge driver for 12v Motor recomendations

    Thanks Les

    Very good advice. I will give the resistor a try. I did not a current increase of 200ma when I stalled it so it should be easy to pick up.
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    Re: H bridge driver for 12v Motor recomendations

    One more thing(s). I soldered a wire directly to the chip from the 12v line. There was a single via on the track I missed doubling up the vias at that side change and its now much better.

    One more...
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    Re: H bridge driver for 12v Motor recomendations

    Let me recap as its been a long thread

    1 I have to control the speed of a motor, a toggle switch is pressed the motor speed needs to start off slow as I want fine control. The longer I hold the...
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    Re: H bridge driver for 12v Motor recomendations

    Its seems the reason I said 25khz is not clear

    Pics with 2 PWM channels have one freq that is shared between the 2 channels and you can only alter the duty. If I'm wrong on this I need to know!
    ...
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    Re: H bridge driver for 12v Motor recomendations

    Doing some research it seems that 25khz is ok for motors

    https://electronics.stackexchange.com/questions/67663/criteria-behind-selecting-pwm-frequency-for-speed-control-of-a-dc-motor


    I wonder...
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    Re: H bridge driver for 12v Motor recomendations

    Hi,

    This the motor LINK its max current is say 700ma tops.

    What I'm finding in practice is that its stalling. But the code ramps up the PWM duty so it does unstick if I wait.

    Running tests...
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    Re: H bridge driver for 12v Motor recomendations

    Hi

    I want to say thanks for all the excellent help I have received.

    At this time my proto board complete with bugs and patches is going to be tested in the wild by myself on a job next week....
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    Re: Advanced timekeeping

    Great stuff

    To add my 0.02 worth as an example of the way I handle code

    I nearly always use an interrupt timer. In that timer I add any timers I need as I'm writing the code.

    There are 2...
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    Re: H bridge driver for 12v Motor recomendations

    Thanks Joseph

    Both are OK as components.

    I have gone from a simple small board to now knowing I have to make a super robust board that is overkill. The client will pay enough for the overall...
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    Re: H bridge driver for 12v Motor recomendations

    Hi Norm

    I could but then I would need another set of ICSP pins :(

    This board is not going well.

    The fans can draw 6 amps! There is noise on the 12v line but the 5v is stable. However the H...
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    H bridge driver for 12v Motor recomendations

    Hi,

    This is my problem

    I need to control a DC motor rated at 12V 600ma
    I need to control the speed and direction

    Currently I'm using a LV8548MC and using the PWM command to control the...
  33. Re: Base biased PNP transistors running at > Pic VDD

    The problem is way harder than I thought

    There is no simple solution apart from changing the feed to 5v for the Leds

    This is what I did. The reg is rated at 1 amp so will be able to supply the...
  34. Re: Base biased PNP transistors running at > Pic VDD

    Thanks

    I doubt an N channel will work with my wiring as its switching 12v and the Led is sinking it directly to ground. BTW that part you recomended is a SOT232 my pads are SOT363

    By the looks...
  35. Re: Base biased PNP transistors running at > Pic VDD

    I think I'm going nuts now

    I looked at the part I referenced and it does not have the resistors. WTF!

    So I now started from scratch. Digital transistor, PNP, 2 elements per chip SOT363 and I...
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