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Reversing polarity for electrolysis project

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by BHinote, Jun 16, 2011.

  1. BHinote

    BHinote New Member

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    Understood... I will adjust the Schematic accordingly...
    I am moving a couple things around on the Schematic and putting a inventory/parts list together.
    After that I am looking up the part to verify if they can be purchased from one place or another... I will be heading down towards Sacramento again this weekend, so I am going to check out Fry's to see if I can pick them up as appose to waiting for them to be shipped. Chances are that something will have to be ordered, so it would then become pointless to pick them up at Fry's...
    Thanks again
     
  2. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Your 99% there.

    You need a single resistor from the junction of U6d(13) and U6e(5) to +5. Make it 4.7K for now.

    The ULN2003
    1. Will not have a + power pin
    2. COM will be unconnnected
    3. GND will be connected
    4. Is not sensitive to unconnected inputs

    One section of the ULN2003 and 1 resistor COULD be eliminated. The resistors reflect this.

    I'll verify the resistor values. Do you have an LED part number/datasheet?
     
  3. ronv

    ronv Well-Known Member Most Helpful Member

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    If you want to PM me your e-mail I'll try to make you a bill of material for Mouser. They have a nice system you can click on the part and get the data sheet and you can one click the order. I'm pretty sure I can get it done before time to order on Monday, I know you are against a deadline on your simulator.
     
  4. dave

    Dave New Member

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  5. BHinote

    BHinote New Member

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    I currently have 3 packages of LEDS. They are as follows:
    1. 5mm Red - 2.6Volt, 28mA, 10mcd (Absolute Max Rating 25 Deg. C, Power Dissipation 60mW, Forward current 28mA Max, Peak Wave Length 650nm)
    2. 5mm Green - 3.0Volt, 20mA, 40mcd
    3. 5mm Yellow - 3.0Volt, 20mA, 55mcd

    BHinote
     
  6. BHinote

    BHinote New Member

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    KISS,

    I have added the Resister to the design you were mentioning, see attached, however I am not sure what your statement means. (i.e. One section of the ULN2003 and 1 resistor COULD be eliminated. The resistors reflect this.)

    BHinote
     

    Attached Files:

  7. ronv

    ronv Well-Known Member Most Helpful Member

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    Guys, I don't think you need all the inverters to drive the leds. The 555 can drive them all.
     
  8. BHinote

    BHinote New Member

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    Ronv,

    This is patterned after your design. How does it look?

    BHinote
     

    Attached Files:

    Last edited: Jun 24, 2011
  9. BHinote

    BHinote New Member

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    556 Timer

    By the way, I am using a 556 timer because I bought one along the way.

    Unfortunately I have lots of parts along the way that will probably not be used, but that was before the professionals came on board... :D

    If I can not return them and the can not be used, maybe I will have to see what makes them explode... That way I will get more "Bang for my Buck". I know that was bad...

    BHinote
     
  10. BHinote

    BHinote New Member

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    Required Parts List

    Here is my take on the parts needed vs. what I already have.

    BHinote
     

    Attached Files:

  11. ronv

    ronv Well-Known Member Most Helpful Member

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    I don't think you need D1. When you take it out R16 should be another 220 ohm.
    I worry about S2 as the rest of the circuit will still be powered. What was your intent for it?
    My comment about the inverters related to the SSR design. I think this will also work and is easier to build, but I can't model it.
     
  12. BHinote

    BHinote New Member

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    Ronv,

    You guys know better than I do, so I can remove D1. KISS had indicated that LEDs should not really have positive voltage going the wrong way, even though 5V was probably not going to do any harm. So I thought I would add it as extra protection...

    MY idea for S2 was to stop the timer so only one side of the H-Bridge would be active and the LED would still be on. Is there a better way to do this?

    I can not model specific components of the SSR design either, specifically the LCC110's, but it makes sense so I though I would buy those components too.

    BHinote

     
  13. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Make R200, R201 closer to 270 ohms, not 390 ohms. ronv's right, the inverters can go if you check the resistor calcs again.

    I fell asleep and didn't get to go over thing with a fine tooth comb.

    But just a reminder for LED driving (sourcing and sinking).

    You have a term Vce(sat) usually from 0.2 to 0.8 volts

    You have a supply voltage: 5V or slightly less than 5V (The 555 won't go to 5V, nor 0 volts) It will get close. You would use these numbers if directly driving LEDs from the output of the 555.

    You have a LED voltage drop, called Vf. It's 1.2 V for the LCC110. Could be 2.1 or higher for other LEDs.

    There is a min/max/typical drive current for LED's. 20 mA typical, 50-70 mA maximum. The LCC110 has a 8 mA typical. Would probably drive at 15-20 mA.

    There is Vbr or V(reverse breakdown) for the LED and all diodes. The mechanism is usually non-destructive. Depends on design.

    There is resistor power rating: (I^2)*R; 1/2 W should suffice

    LEDs age, output does diminish over time. There is lots of variation.

    Basic formula is (5-Vce-Vf)/I for that series resistor.

    I had intended in one of the designs to place the LED's in the optocouplers in series, hence R was higher.

    These guys: http://www.electro-tech-online.com/custompdfs/2011/06/156946.pdf Bi-color 3-lead LED's are avialable in common anode/common cathode versions. Not a real common part, but usefull. They glow yellowish when the polarity alternates fast enough. That particualar part is from www.jameco.com This is when panel space, cool factor come into play. I designed a peak detector, pulse extender and I used one. 50 Hz signal. If it exceeded +-10V, the approprite color showed up for 1 second, so you can see it.
     
  14. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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  15. BHinote

    BHinote New Member

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    KISS,

    You are right... I should be using the graphs and I should have a better understanding of everything you indicated about sourcing and sinking, terms, Vce(sat), Vf, Vbr, (5-Vce-Vf)/I, etc... However this truly is my problem, I do not understand a lot of these things and some of the things I thought I understood have turned out to be wrong as well.

    I hate to have come so far only to be so confused right at the end that I am not sure if I should order parts or not...

    I have tried not to through my hands in the air and wait for someone else to do it all for me, but it is those things that you mention that I defiantly do not have a grasp on at this moment. I am trying to follow along, but I am not sure there is enough time for me to comprehend all that is at play... I can perform the calculations from the formulas that you may provide, but I do not currently have the ware with all to understand what and where these values come from...

    As always, your help has been greatly appreciated.

    BHinote

     
  16. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    I think for the most part your set. I'll continue to look at it. Migraine, recovery and catch-up takes a while. The main trigger is weather changes. Crief comments are:
    These are mostly questions.

    1. Need a small cap on the output side of the 5V regulator (0.1 uf) should be fine.
    2. I'm still confused about the manual mode of plating polarity (S1)
    3. Reverse polarity protection? A fuse/ and reverse biased diode across the 37 V input is one such way.
    4. Misc parts. (assuming breadboard)
    5. Connectors to bring switches, pots outside of the board?
    6. Breadboard choice, if your going that route?
    7. In the SSR version, rather not try to eliminate the inverter/drivers.

    Fig 8, here http://www.electro-tech-online.com/custompdfs/2011/06/P2514.pdf is what I used for resistors for a 0.042 hole.

    I've been happy using pattern I http://www.electro-tech-online.com/custompdfs/2011/06/P2514.pdf . See the next page.
     
  17. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Plating mode select switch suggestion

    I may have a better way to force the direction. Threshold and trigger are tied together, so locate this point, call it C.

    Take an SPDT ON-OFF-ON switch and tie the center terminal to C. Tie an outer terminal to Vcc and tie the other outer terminal to ground.

    So, the switch would be labeled, FWD, Normal, and REV.
     
  18. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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  19. ronv

    ronv Well-Known Member Most Helpful Member

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    The LEDs should not be reverse biased more than 5 volts, but since there is 5 volts on the other side of the LED it is not reverse biased at all.

    If you remove the reset pin from +5 and add a resistor (10K) from reset to +5 instead, you could then use the switch to ground the reset pin and stop the timer.
     
  20. BHinote

    BHinote New Member

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    Yes this will work beter.

    Thanks again for you help.

    BHinote
     
  21. BHinote

    BHinote New Member

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