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  1. foTONICS

    stepping down voltage twice

    So I wired a 7812 and a 7805 in series with the input to the 7805 connected to the output of the 7812. I was expecting 12V and 5V respectively but I got instead 11V and 5V. what happened to that extra volt? I supplied the 7812 with 15V (even brought it up to 20V same issue). I'm aware of the...
  2. foTONICS

    l293 motor driver

    The datasheet says the motor logic inputs are TTL compatible. I was playing around with a prototype and accidently wired it up as 0 and 12 V instead of 0 and 5 but the circuit behaved as expected. can this chip handle 12V on its input pin or will it become damaged after a while? I can't find...
  3. foTONICS

    identifying this terminal block

    Hey all, I'm building this board and I want to use up some spare parts I had from some harvested pcb's. I have this terminal block that I want to incorporate into an eagle drawing but it doesn't have a part number and since I'm new to eagle I'm having a hard time deciding which one it could be...
  4. foTONICS

    Powering a solar tracker

    should my undervoltage protection circuit be before my tracking circuit or just before the actual motor, or both? ive attached a picture of something i came up with after a little research and after running it through multisim it still seems to let some voltage through (even when I decrease...
  5. foTONICS

    Powering a solar tracker

    So I am working on this solar tracker circuit for my final project (I posted on here a couple weeks ago asking for help regarding a couple of things). I want this thing to power itself without relying on any type of battery system, what kind of erratic behaviour can I expect as the sun starts...
  6. foTONICS

    solar tracker

    So I was running just a small part of the circuit ( IC1a, C1, C2, R1, R2, R3, R4, VR1, the photoresistors, and the 3904 that the output controls) and was wondering what the purpose of the feedback is? I understand how and why feedback is used but when I take out the 1M feedback resistor I dont...
  7. foTONICS

    diy logic probe

    I guess my question was why sink instead of source, is it because this comparator can sink more current than it can source or is there a different reason?
  8. foTONICS

    diy logic probe

    Oh my I forgot about that thread. Judging by this new submission it looks like I've come a long way since then. I see your point about the invalid level, I was just designing the probe for more of an educational tool than actual lab equipment. Thanks again for the help. On another note, why...
  9. foTONICS

    diy logic probe

    I was working on my own logic probe design that met the following conditions: 1. run off 5V 2. Each logic level (high, low, inalid) will have its own LED 3. No LED should light if the probe does not touch anything I have attached a few sketches that I drew up, I'm open to input and the...
  10. foTONICS

    solar tracker

    So I did a little research and this is what I get from it. If the + input of IC1a is greater than the - input then the output goes into high impedance causing LED2 to turn on cause it sees the 9 volts. But if the opposite is true it sinks the current through R4 turning off LED2?
  11. foTONICS

    solar tracker

    OK this is making more sense now, thanks a lot for all the help. It made things so much clearer
  12. foTONICS

    solar tracker

    Ya I understand that they are all on one chip. I've just never seen a circuit where their outputs are powered from a separate source. I'm used to seeing simple versions where only the inverting and non inverting inputs are powered
  13. foTONICS

    solar tracker

    So the 9V part is where I get a little confused. I didn't know you could power the op amp like that. So the supply rails shown for that first IC aren't shown for clarification purposes or they are purposefully left disconnected. If this is the case we never went over that in my linear circuits class
  14. foTONICS

    solar tracker

    Hey all, So I wanted to design a solar tracker for my final project and found this very helpful schematic online. I understand almost all of it except for a few things. 1. Why the feedback loop on IC1a and IC1c, is it some sort of gain control? and why would it need to be tied to 9 volts...
  15. foTONICS

    c programming

    ++++1 for this. Last summer I taught myself basic assembly programming for the PIC16f627a to prepare myself for the uController class I had coming up. We ended up using the HCS12 board which runs on a motorola and used the asmIDE which was COMPLETELY different than the .asm and MPLAB I was used...
  16. foTONICS

    VHDL

    Line 17 was the process sensitivity list, namely "process(clk,w_s)" I have made a little headway since I last posted my question, I have been able to shift the data right but haven't been able to parallel load it. This is mainly due to me getting rid of the first part of the if statement...
  17. foTONICS

    VHDL

    So I've been given an assignment to create a 4-bit parallel load, serial in/serial out shift register. Here is what I have so far: So my idea was that during a HIGH "w_s" signal my data would shift right by this code: and during a LOW signal it would run this code: When I run the code...
  18. foTONICS

    connecing a PICkit 2 => PIC24EP128GP

    thanks a ton, this is very helpful
  19. foTONICS

    Searching for a PIC dev board

    ya that's pretty much exactly what I was looking at: http://www.mikroe.com/easypic/?gclid=CLeOn9WAq7UCFYZcMgodUzcASQ I just didn't want to go overboard since I'm still new and figuring out what direction I want to go, but one of these is looking better and better each time I look at it...
  20. foTONICS

    connecing a PICkit 2 => PIC24EP128GP

    Looking up the schematic for the PICkit 2 I have: pin 1: Vpp/MCLR pin 2: Vdd Target pin 3: Vss (ground) pin 4: ISCPDAT/PGD pin 5: ISCPCLK/PGC pin 6: AUXILIARY and looking at the datasheet for the PIC24 I have the corresponding pins: pin 1: MCLR pin 13: Vdd pin 19: Vss the next...
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