[chbot] Car 12v supply to 5v VCC.

[Geoff]

You can actually find 12->5v step downs locally in NZ for cheap enough. All
car USB converters do exactly this, and can be had on trademe for a couple
dollars:
https://www.trademe.co.nz/computers/cables-adaptors/usb/listing-2220387680.htm
If you have a dollar-store-thing near you, they probably have them as well
for $4-5. In bishopdale mall there's a "Party Dollar Store" that I used to
pick up this sort of thing from.

Even if you're not using it in the cabin of the car, you can open it up and
extract the PCB so you can solder wires to it. The ones I used had a single
screw that held the whole thing together.

Is the output stable? Well, from a clean 12V supply, I've been running a
raspberry pi for the past two years, and it's still working. No idea about
what a racecar would do to it.

Geoff

On Sun, Jul 7, 2019 at 5:15 AM <m.beckett at amuri.net> wrote:

> +1 on the insulated.
>
> The vibration will range from fairly solid thumps to higher frequency
> vibration, so rubber isolation will be your frend.
>
> Large components will appreciate a dab of a neutral cure silicon to help
> them hold in place rather than relying on the component leads.
>
>
>
> The electrical noise is not likely to be any more than a normal car. Race
> cars tend to have lower amperage alternators and the battery while smaller
> is not as taxed as a normal car.
>
> Choke and capacitor (both large uF and smaller 0.1uF) across the incoming
> should be enough.
>
> You can have someone check the 5v line with an oscilloscope if you have
> any doubts.
>
>
>
> cheers
>
> Mark
>
>
>
> On 2019-07-07 13:32, Mark Atherton wrote:
>
> Hi Daniel,
>
> First on your list would be my first choice, only because of the size of
> the regulator :) Also appears to be available on Trademe for a
> few-more-bucks https://www.trademe.co.nz/Browse/Listing.aspx?id=2212079583Datasheet
> for the XL6009 part is https://www.sunrom.com/get/283300 indicates that
> the part is up to 94% efficient, and has a wide input range - 5-32V. Power
> spikes on car 12V rails can be quite large, so having a regulator that can
> tolerate a 32V spike is heading in the right direction.
>
> As Volker says, mechanical vibration can be a killer; all components need
> to be well secured; screwing or gluing modules to an insulated substrate
> may work well.
>
> Looks like a great project, links to photos of the project / vehicle
> appreciated.
>
> Regards,
>
> Mark
> ------------------
>
> On 7/07/2019 9:04 AM, Daniel Powell wrote:
>
> Sorry for the intrusion with something bound to be a simplistic and rather
> rudimentary question given my lacklustre knowledge in electronics.
>
>
>
> I’m currently developing an ESP32 wrover, CAN Bus based dash for my race
> and rally car. I’ve already prototyped the dash using a Nano (which was too
> slow to capture every frame), then prototyped all but the 7 segments using
> the ESP32 (7 segments are 5v LL, ESP is 3.3). I’ve recently transferred it
> to protoboard (which I’m simply using as a flat substrate to level and
> mount the modules). I need to reliably convert the car 12v to the 5 volt
> required for VCC on most of my devices. I’ve purchased a handful of
> different aliexpress 3A DC to DC voltage stepdown regulators and a 1.8A
> buck converter.
>
>
>
> I wondered, given the noisy power environment of a race car, which, if
> any, would be best to provide 5v to my dash.
>
>
>
> Unfortunately my pics break the 40k email list limit, as such I’ll include
> links to the devices.
>
> https://www.aliexpress.com/item/32280431843.html , LM2596HVS, XL4005 and
> XL7015
>
> https://www.aliexpress.com/item/32961984080.html , 12V LM7812
>
> https://www.aliexpress.com/item/32921703886.html
>
>
>
> I’ve previously used a radio control UBEC to convert the car power to
> something I could pump into a raspberry pi, through it’s on board
> conditioning, however I’ve never bothered to understand the fundamentals of
> power supply or how to smooth it such that I don’t damage componentry.
>
>
>
> https://www.aliexpress.com/item/32920672534.html
>
>
>
>
>
> Help genuinely appreciated.
>
> For those of you interested and wishing to punish yourselves further.
> TTGO ESP32 wrover (on board CAN)
>
> NS65HVD230 CAN  transceiver.
>
> MAX2719 8x8 matrix (gear display)
>
> 4 x TM1637 - 7 segments (switched pages of 4 pressures/temps/alerts)
>
> 2 x 8 WS2812 Neopixles. (RPM and colour change for alerts).
>
> TXS018E 8 channel logic level converters (yet to test).
>
>
>
> Regards,
> Daniel Powell.
>
>
>
>
>
>
>
>
>
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