OKR-T/10 Passthrough

[EvilBetty]

Found this today. $155 is a little high for this device I think. (Though if it was in stock I probably would have bought it.)

*NEW* Zorro 3-6v 10A/50W Passthrough


I can make this. OKR-T/20, A 12v power supply, switch, mini-voltmeter, 510 connection, appropriate pot and resistors, fuses, and tactile switch.

Found this schematics on another forum, though I've seen Mamu's and Breakthru's posts here too. Hoping they'll chime in here.

Would alter it obviously to work hardwired only.

Preferably off of a 12v car adapter and 12v AC adapter. I have access to some nice brick power supplies 12v ~ 18A.

Wondering if I need the MOFSET. Seems unnecessary with a polarized power connection. Wondering if the pot and resistor combo for PIN 5 would be the same using this power supply.

 

[DrMA]

No need for the fet, that's used as reverse polarity protection with loose batteries. Also you wouldn't need the 6V Zener diode (low V cutoff) and no need to change the trim resistors. You will need a 5K resistor instead of the 1K shown in the diagram between pins 3 and 6, if you go to a 12V supply, otherwise the OKR will draw too much current on the remote on/off pin.

 

[dropsomegears]

Silly question. Why the fuses? I know for DNA mods its needed. But I've seen several OKR mods with no fuses.

 

[DrMA]

Silly question. Why the fuses? I know for DNA mods its needed. But I've seen several OKR mods with no fuses.

Fuses protect the batteries against shorts that may occur in the wiring or circuitry inside the mod. They aren't technically needed, but provide cheap insurance against potential catastrophic failure.

 

[dropsomegears]

Fuses protect the batteries against shorts that may occur in the wiring or circuitry inside the mod. They aren't technically needed, but provide cheap insurance against potential catastrophic failure.

I was like ok not needed then read CATASTROPHIC FAILURE. lol Soo 5amp should be enough protection lol ?? Thanks I had a few lipos go catastrophic on me but it was in a R/C application and luckily far away. But unlucky as well cause I had to run all the way out there to save as much of the car as I could lol.

 

[EvilBetty]

Fantastic. Thanks for the reply. Time to place a parts order

No need for the fet, that's used as reverse polarity protection with loose batteries. Also you wouldn't need the 6V Zener diode (low V cutoff) and no need to change the trim resistors. You will need a 5K resistor instead of the 1K shown in the diagram between pins 3 and 6, if you go to a 12V supply, otherwise the OKR will draw too much current on the remote on/off pin.

 

[EvilBetty]

I'll be fusing the 12v car cord with a 10A fuse. Might do the same in the connector off of the power supply as well just to keep from burning it out.

 

[mamu]

Good timing EvilBetty (lol love the name ) - this is a project I've got parts coming in.

I plan to use a 10A fire switch, so won't be using pin 1 and with the passthrough don't need undervoltage protection with the zener diode.

Here's the wiring I plan to use...

 

[DrMA]

Mamu,

Some of your older OKR designs also had a 22uF cap on the output side. Why aren't you using one here?

 

[mamu]

My original OKR design was based off CapeCAD's schematic where he used 10uF, 16V input and output caps. I also talked with a Murata rep and he recommended caps as a buffer/cushion from repeated and frequent firing to ease the stress on the batts and the converter. Easing the stress on the batts and converter from repeated and frequent firing also helps with longevity.

And since I'm not using the control pin with this passthrough and doing a full power-up with each hit a bit of a buffer with an input cap should help there, but the output cap is not really needed. The atty doesn't care about an output cap and if I have problems with the voltage reader not working correctly at the output, I may add an output cap. But so far aok with that.

With regards to using an input cap with the OKR via passthrough - AC adapters can put out a lot of noise so an input cap may help filter some of that out.

I'm using a 22uF MLCC cap on input - it's small, inexpensive, and has very low ESR (C3225X5R1C226K250AA).

 

[EvilBetty]

Good timing EvilBetty (lol love the name ) - this is a project I've got parts coming in.

I plan to use a 10A fire switch, so won't be using pin 1 and with the passthrough don't need undervoltage protection with the zener diode.

Here's the wiring I plan to use...

Awesome.

Which trim pot are you using? I'd like something that doesn't stick out too far, but is also usable without finding a penny or screwdriver.

Why still 2x5A fuses? I was just gong to put a 10A blade fuse in it.

 

[mamu]

It's your option what fuse you want to use, but I use 2x fuses in parallel to half the fuse's internal resistance so it has least effect on the circuit. Paralleling 2 fuses doubles the current and cuts the fuse's internal resistance by half. Plus if space is an issue inside the case, 2x 5A fuses are smaller in width and height than 1x 10A fuse.

200 ohm POT (PT10MH01-201A2020) (mouser)

Shaft for 200 ohm POT (JPEPL5012NE or 5116) (mouser)

POT knob of your choice that accommodates the size of shaft you've chosen (if using a shaft, a knob is not necessarily required)

 

[EvilBetty]

Ah cool, hadn't thought of that. Good idea.

Thanks for the part numbers.

Do you have a full parts list from mouser you recommend?

 

[deemer]

I am working on one of these to upgrade my old OKR 6 PT. I am having trouble finding a nice 10a switch though. Anyone have a link they are willing to share? Or can I use a switch rated 48v 2a dc?

http://www.digikey.com/product-detail/en/GPB553A201BB/CWI260-ND/3193527 is my current leader.

 

[Joshleeman]

Good timing EvilBetty (lol love the name ) - this is a project I've got parts coming in.

I plan to use a 10A fire switch, so won't be using pin 1 and with the passthrough don't need undervoltage protection with the zener diode.

Here's the wiring I plan to use...

Was wondering if you could share a complete parts list for this build from scratch? I dont have any preferences, would like to use exactly part for part what you use and know works if possible. Thanks!!