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

Tue Jul 9 07:38:18 BST 2019

Have you considered running from SLA or other rechargeables so that you
don't have to deal with dirty 12V?

On Sun, Jul 7, 2019 at 7:35 PM Geoff <sdfgeoff at gmail.com> wrote:

> 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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