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Capacitor as backup to 12v train camera system power

Discussion in 'Power Electronics' started by mcates, Apr 3, 2019.

  1. BobK

    BobK

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    I guess his trains take to the air for 3 seconds every now and then.

    Bob
     
  2. Alec_t

    Alec_t

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    Jul 7, 2015
    The TS hasn't said if his 'unique' setup track supply is AC, but if the regulator input dips below the voltage of the proposed battery then the simple diode-OR arrangement I suggested in post #8 would need to be replaced with a more complex one to prevent continuous pulsed discharge of the battery.
     
  3. mcates

    mcates

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    Apr 3, 2019
    First, thank for your responses. THANK YOU! Sorry was out of town at sons baseball.

    What brings it up is that they wanted a High Def camera on the train for a clear and crisp look. I could not get it with an analog style that they liked. Then the train is mounted 20 feet up around the ceiling and accessibility is difficult. There are some unusual turns that my rattle the train and cause a momentary loss. Due to the location and accessibility issue, I need a way to ensure power and transmission but without a power/battery/backup at times the power loss causes the transmitter to go out and requires a reset so then we have to do a full reset of the train. Now every night the system is turned off and if I had any sort of battery backup unit in the train car it would drain every night and eventually go bad as there is no way to turn it off where it's located. So the only options were some sort of battery solution with a relay or a MOSFETT (still not understanding how these work) or a small capacitor bank that will get me a few seconds during those momentary outages on a train. But someone said in another post that my capacitor will run down and the power from the tracks will not be able to refill them upon restart the next morning. So I am concerned that I am going to be in the same boat of needing a relay or MOSFETT to monitor power from the tracks and upon power being turned off, wait 3-5 seconds and then kill the relay line to cut power to camera and transmitter thus not draining the battery backup or capicator backup. I understand it I just need help on how to build it. I have all the parts or will get then if needed.
     
    Last edited: Apr 8, 2019
  4. mcates

    mcates

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    Apr 3, 2019
    Thanks for the response. Sorry was out of town at sons baseball.

    AC power is connected to the trains power supply and converts to DC voltage.

    But now from what you are saying I am going to need something that when the power is off the tracks at night it will still drain the capacitor and from what your saying the track power of 12v-18v is not enough to charge the bank within a few minutes?

    If so then I am still in the boat of needing a relay or mosfett to monitorthe track power and when its turned off for the night to wait 3-5 seconds and cut power to the camera and the power to the transmitter. Then they won't drain the capacitor or battery and when power is restored the next morning the relays will kick in and restore power to the 2 devices.

    I just don't know for sure what relays or mosfetts I can use and how to wire them into my diodes/capacitors/booster/usb system.
     
  5. mcates

    mcates

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    Apr 3, 2019
    I can adjust the power as need on the tracks from 0-20 volts. But I am staying at about 14 to power a booster that then I power my camera and transmitter off of.
     
  6. Alec_t

    Alec_t

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    Jul 7, 2015
    I may be confusing you with another poster, who was proposing to power the tracks with unsmoothed DC and use on-board processing on the train.
    Suppose you have a 12V battery/supercap as backup. Would you want to have a DC track voltage less than 12V?
    If you can keep the track voltage above the battery voltage at all times except during those brief glitches then there won't be a continuous discharge. Roughly how often would you expect a 1-3 sec glitch to occur? That will determine if keeping the battery charge topped up during normal running is feasible.
     
    Last edited: Apr 8, 2019
  7. mcates

    mcates

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    Apr 3, 2019
    1. Using a bridge and then schottky diode to Capacitor in #2 below
    2. Yes, I want to set the voltage high enough so that it can charge my capacitor bank below.
    Shaluoman Farad Capacitor 2.7V 500F 35X60MM Super Capacitor With Protection Board
    3. Then it feeds the booster and powers camera and transmitter and all should work well for the day
    4. It may glitch 1 to 4 times but for 1-3 seconds at max.
    5. At nights the power is turned off and this will drain the capacitors above. When they return the next day and power the track on will the system be able to charge up the capacitors back to 90-100%? If not I need to figure out a way to add a relay to shut the power off after 3 seconds or more to the camera and transmitter so that not to drain the capacitor correct?
     
  8. mcates

    mcates

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    Apr 3, 2019
    Yes, its 110 voltage converted to dc power to the tracks. I am not sure what this causes or if I need to add something to clean the power or anything else. If so please advise me of what I need to add something to clean signal or modify it in any way.
     

    Attached Files:

  9. mcates

    mcates

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    Apr 3, 2019
    No it just rocks and seems to loose a solid connection from the tracks.
     
  10. mcates

    mcates

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    Apr 3, 2019
    Hello,
    Can I use a relay like these to monitor the track power and once power is turned off to wait three seconds and open the circut thus turning off the camera or transmitter?
    If so can you explain the wiring as I do not understand how to wire it.
     

    Attached Files:

  11. BobK

    BobK

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    Jan 5, 2010
    The capacitor should be powering the camera only during the outages, when track power is available, it should be running off the track power.

    A properly sized capacitor will charge in less time it needs to provide power, possibly even way less, so a matter of seconds.

    A 500F capacotor is not properly sized. It is way too large and would cause issues with charging.

    I thought we had settled on a board that had a 12V rating and about 0.7F. That is the right size.

    A 0.7F capacitor will charge from zero to 12V in 8.4 seconds when charged with 1A.

    Bob
     
  12. mcates

    mcates

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    Apr 3, 2019
    Bob,
    Ok but how long would a .7f last and do I need to get multiple to get me up to necessary voltage? I can do that just need a little more guidance.

    I do need the capacitor in front of the camera and the transmitter. both take USB 5v 1.5 amps max. Need to keep both powered.

    track power 12v to bridge to schotty to ....

    Not sure how it goes from there.

    Those 2.7v 0.7f capacitors are hard to find!
     
    Last edited: Apr 8, 2019
  13. BobK

    BobK

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    Jan 5, 2010
    You do not need the Schottky diode after the bridge, the bridge is diodes. Presumably, your bridge is feeding a step down switching regulator to supply the 5V. The capacitor could go either of two places, before or after the step down. If before, it would required higher voltage rating. If after it would have to be larger to provide more current.

    The 15V capacitor bank you linked to here:

    TURNIGY VOLTAGE PROTECTOR 783333uf (3sec) STOP RC RECEIVER BROWN OUTS
    https://hobbyking.com/en_us/turnigy-voltage-protector-783333uf-3sec.html

    Seems to be about right. It connects directly to the bridge and to the step down converter. It is designed to provide current for a limited amount of time, which is exactly what you need.

    Here is another example:

    https://www.amazon.com/OTGO-Capacit...ateway&sprefix=supercapacitor+,aps,134&sr=8-3

    Bob
     
  14. mcates

    mcates

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    Apr 3, 2019
    Bob,
    I have that turnigy one coming. Wil takes a look at the Amazon one as well.
     
  15. mcates

    mcates

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    Apr 3, 2019
    Bob,
    As a test it is working great with the capacitors I have. Last 5 min on those Shaluoman Farad Capacitor 2.7V 500F 35X60MM Super Capacitor With Protection Board. I do have one question about my bridge rectifier. I have two types and both are getting real hot. Would that be because my power unit can give up to 5 amps and 20 volts? I have tried both of these below and I sent my power supply to 12v and 2amps but it got hot as hell.

    KBP307 Flat Bridge Bridge Rectifier 3A/700V
    2A 1000V 2W10 Bridge Diode Rectifier CYT1014

    I ordered a couple of these as I am not sure if I have under power bridge rectifiers?
    6A 600V BRIDGE RECTIFIER GBU6J
    NTE Electronics NTE53004 Full Wave Single Phase Bridge Rectifier, 10 Amps, 1000V Maximum DC Blocking Voltage


    Or what bridge rectifiers do you recommend??? I definitely need one as they can through the train in reverse and it will blow the system.


    Thanks and I hope to have the TURNIGY ones in by the end of the week.

    THANK YOU again for all your help!

    Mike

     
  16. BobK

    BobK

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    Jan 5, 2010
    I give up.

    Bob
     
  17. Alec_t

    Alec_t

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    Jul 7, 2015
    Can you post a link to your power supply's specs/datasheet?
    The supply might not like the huge current surge charging the supercap up from zero.
     
  18. BobK

    BobK

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    Jan 5, 2010
    Not to mention the fact that the cap is rated at 2.7V.

    Bob
     
  19. Alec_t

    Alec_t

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    Jul 7, 2015
    Presumably the individual caps are series-connected, but in the post #34 link there is no visible circuitry for equalising the cap voltages as they charge/discharge :confused:. Also, the module is rated for an input voltage of 11.1V max, so that could be a problem if the TS uses 12V on the track.
     
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