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mikee

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Posts posted by mikee

  4. brenner burner mod for pic16f84 and pic18f425

    in Design Concepts

    Posted

    hi all.

    I just threw a burner together: got Brenner 18 and burned a bootstrap loader into a pic18f425, then (using Brenner 44) burned a pic16f84 with a test prog.

    Glad to report all was perfect from start to finish. Works great at full speed.

    No printed board - just a quick pin to pin hard wiring, scrap of perf board, and wired using some strands of recycled hard-drive flat ribbon cable (the fine-single stuff).

    Recycled a 25 pin D plug from an old printer cable, used just 1 ground (pins 14 to 18 all commoned to 1 wire), 4 Data and 1 Ack.

    No screen, but short cable (100 cm approx).

    Not happy with having to readjust MCLR voltage every time I change from 18F452 to 16F84 so added attached mod.

    Note: I used 4k7 presets recycled from old Sony CD drives. (My stuff is always recycled except for the PICs of course. (anyone know of a source yet?)

    Hope this is of some use. cheers all and thanks.

    adj_mod.JPG

    adj_mod.JPG

  5. Instant and cheap PCBs.

    in Tips & Tricks

    Posted

    This is added in case anyone is still playing with the thing:

    I played around with lazer/toner/glossy paper to make circuits boards and met with varying success.

    The paper is most important, and I found some which was intended for printing glossy photos (a certain Kodak paper from Staples), and the quality was also affected by the toner etc.

    Interesting, but very time-consuming. I might get into it properly one of these days, and see if there is a solid repeatable method.

    I have half of a board left over from those days (a Pic18F452 Midi Saxaphone) and you can just make out the two Xtal (10Mhz crystal) capacitors still in situ.

    Notice I avoided taking tracks between pins. It can be done but its not worth the effort.

    cheers all

    sax_1.JPG

    sax_1.JPG

  6. rotary encoder question

    in Parts Questions

    Posted

    yeah thanks for that avogra .

    It seems that the control in question is from a broken Pro-DJ CD/karioki thing. (Soundlab G064E8).

    There are also a couple of sweet blue backlit LCD displays which seem to be intended for track position, pause, FF,REW, speed, etc etc. Pity about these not being a couple of lines of text.

    The controller chip also encodes up to 30 keys, and outputs data in serial form. What a shame so much technology is wasted.

    Thanks again for info.

  7. rotary encoder question

    in Parts Questions

    Posted

    hi there everyone.

    I got a part which I am trying to identify, I wonder if anyone has some info:

    Rotary encoder with 8 connections.

    Two knobs: Outside knob is centered and spring biased rather like old synth pitch bend control.

    Inner knob is standard Rotary encoder action.

    The only markings on the thing is as follows:

    j (then what seems to be an i in a circle) 5M 14.

    No switch is fitted.

    Anyone got any ideas?

    Thanks all.

  12. LOG taper faders turned into pseudo-LIN taper?????

    in Tips & Tricks

    Posted

    Yeah, thanks for the input all.

    Thanks LyleHaze. I did mean pulling down from +5V to ground (0V), which must, of course be a negative-going direction, its just old Logic speak I'm afraid. I was brought up to believe that moving from zero to a higher potential is positive-going, and from pos to a lower potential, neg going. Of course moving from zero in a negative-going direction will see the end of any standard chip, if applied to an input. It's all relative.

    Your thoughts on the leds etc made sense.

    The idea of using op amp followers (resistance converter-buffers) came up a while back, as I have lots of dual jfet input op amps on the same scrapped mixer, and I am still toying with the idea. Getting the supply voltages correct - so as to have a control output of 0V to 5V - is a bit of a pain, especially if trying to eliminate the use of dual polarity supplies.

    Its all open to happy experiments though, and that's what its all really about.

    Liked your graphs. Never used those packages before, I tend to employ Visual Basic to calc and display such data.

    Regard all.

    (My name's Bond, Co-valent Bond, as Enrico Fermi might have said.)

  13. LOG taper faders turned into pseudo-LIN taper?????

    in Tips & Tricks

    Posted

    Thanks for the quick response LyleHaze, I understand what you say.

    The method I used for my spare log faders, although wasteful, actually straightens out the log curve to a great extent, thus allowing the new faders to function in a less cramped manner, than the original log-law faders.

    The problem was that I had a bunch of 100mm faders, rotary pots and switches stripped from an old Allen & Heath SR416 pro mixer, and as  these components are pro-quality Alps components, I felt it was worth while attempting to use them, albeit after some additional practical modifications.

    I also have Alps a bunch 100K lin center-indented rotary pots, (each fitted with a colour-coded knob) and I use each to drive an emitter follower, such that the resultant output voltage ranges from 0.3V to about 4.8V, this range, I am sure will be adequate to control various synth pots.

    There are also some Alps non-indented 100K log rotary pots, and in this case I added a 12K resistor between +5V and the wiper, the result is a marked improvement over the Logarithmic curve, and again a component has been utilized, rather  than thrown away.

    I must stress however, that I have yest to get a core module up and running, so I don't know what the actual effects of my mods will be, as I have only used a meter to test the things out. Your experience of the MBox and the effects of using log pots is helpful to me.

    As for the switches, they are Alps dpdt latched push switches, of quality gold beryllium contacts, fitted with nice little caps. Why waste them? So I use one pole to feed a led, and the other pole feed a little circuit, which provides a negative-going pulse each time the switch is pressed, this is fed to the DINX4 inputs, and hopefully will be interpreted as a 'normal' button pressed to provide a logic 0.

    When the switch is depressed (ON) the led lights up and a logic 0 pulse is provided. When the switch is depressed again (OFF) the led turns off, and another logic 0 pulse is sent. This at least will save on a load of chips and DOUTX4 boards, and if the serial read/write routines in the core are disabled, might help reduce the load on the chip, and perhaps leave the extra space for other stuff.

    (An added benefit of using such latched switches is that they are able to drive higher currents and voltages than the chips on the DOUTX4 boards, which opens the door to using more interesting indicator lamps).

    By the way, I understand the problems which might arise when using 100K pots rather than lower resistance 10K ones, but I wonder if anyone has actually experienced the effects of using such high values in practice. Would some decent screening help the matter? I only ask because there must be plenty of people with high-value pots, but unable, or unwilling to utilize them.

    Thanks again LyleHaze for your interest, Ive downloaded the graphs and will look at them later.

    Regards all.

  15. LOG taper faders turned into pseudo-LIN taper?????

    in Tips & Tricks

    Posted

    Hi all.

    In my local council recycling center, I found a 16 channel pro mixer desk in a bad state of repair.

    Noting that it had lots of excellent Alps 100mm 10K Ohm Log faders, (plus lots of 100K Lin center-detented pots etc etc) I thought they might be good in a Mbox64.

    Problem is that they are Log law tapers, and it seems that Mboxes don't like log pots. (What is the effect by the way?)

    As I had at least 18 faders, I decided to use two faders arranged in parallel, with one fader inverted. The end result is a fader of 5K Ohm with what seems to be a pseudo-linear taper.

    I know this is awfully wasteful, and I also end up with 5K pots rather than the standard MB 10K, but what the hell, and my power supply (being from a pc, minus noisy fan) can handle the extra bit of current easily.

    Anyway, they work for me  ;)

    I hope this input is helpful in showing what might be possible when faced with difficult situations.

    Cheers all

    Here's how they are wired up:

    pots.JPG

    pots.JPG

  17. Log to lin pot conversion using lookup table????

    in MIOS programming (Assembler)

    Posted

    Hello all you MB nuts.

    I am a newbee, (very first post) constructing a Midibox64, but I want to use some excellent log-law pots which have been gathering dust for aeons.

    Midibox converts analog values from controller pots to MIDI-compatable data (integers in the range of 0 to 127). It assumes the use of lin pots, and applications such as Ableton Live must automatically convert all controller data, which are meant for volume faders, into log law.

    I would like to insert a look-up table (approx 128 lines of code) and a call to the table as soon as any pot changes, the table is filled with linear values for conversions. The end result would be outputted MIDI data with corrected (linear) values from logarithmic audio taper pots.

    I wonder if anyone might help with some questions:

    Is there sufficient room left in a pic18f452 for such a table, and if so what other problems should I be aware of?

    Am I correct in assuming the following functions are required:

    MIOS_AIN_Pin7bitGet

    MIOS_AIN_PinGet

    MIOS_AIN_PinLSBGet

    MIOS_AIN_PinMSBGet

    I hope this all makes some sense to someone.

    thanks and best regards to all.

    ***  I have just realised that a search under "logarithic" almost provides the answer:

    http://www.midibox.org/forum/index.php/topic,1182.0.html

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