12VDC to 3.3VDC Stepdown DIY

[FlashGordon]

I am attempting to build a garage door remote for use on my motorcycle using a small remote and a handlebar mounted momentary push button switch. What I would like to do is remove the CR2032 battery and use a stepdown converter to wire directly into the motorcycle’s 12VDC system as I’ll be putting the remote circuit board inside the headlight housing. Is this possible and, if so, is there anything I should be concerned with such as heat or anything, and what protection can or should I add?

Appreciate the help and suggestions

 

[Moley]

You can pick up buck converters on ebay or amazon for a couple of pound/dollars that will do the job. An example would be On Ebay You will need a multimeter to set up the output voltage

 

[FlashGordon]

You can pick up buck converters on ebay or amazon for a couple of pound/dollars that will do the job. An example would be On Ebay You will need a multimeter to set up the output voltage

Yes, already have my eye on some through Amazon that will do 1.8A @ 3.3V. The description mentions heat, so I am assuming it would need some sort of sink to dissipate that. I currently have a Schottky Diode mounted in the bucket for a set of projector lamps that will go on when I have either the fog or driving lamps lit, and this is then mounted to the metal bucket using thermal adhesive after all electrical connections were heat shrink covered. Should I do the same for the converter?

 

[James]

remote controls like that only draw power when the button is pressed.
power draw is so small that i would not expect you to need a heat sink.

 

[FlashGordon]

remote controls like that only draw power when the button is pressed.
power draw is so small that i would not expect you to need a heat sink.

Perfect. Thank You!

 

[alasdairmp]

Yes, already have my eye on some through Amazon that will do 1.8A @ 3.3V. The description mentions heat, so I am assuming it would need some sort of sink to dissipate that. I currently have a Schottky Diode mounted in the bucket for a set of projector lamps that will go on when I have either the fog or driving lamps lit, and this is then mounted to the metal bucket using thermal adhesive after all electrical connections were heat shrink covered. Should I do the same for the converter?

The CR3032 can only supply a few tens of mA. I would use something that could do 100 mA (0.1A) for (not 1.8A) this purpose - like the L78L33ACZ plus a couple of 0.1 uF small capacitors. Easier and safer long-term.

https://uk.farnell.com/stmicroelectronics/l78l33acz/ic-v-reg-3-3v/dp/1467768

 

[FlashGordon]

The CR3032 can only supply a few tens of mA. I would use something that could do 100 mA (0.1A) for (not 1.8A) this purpose - like the L78L33ACZ plus a couple of 0.1 uF small capacitors. Easier and safer long-term.

https://uk.farnell.com/stmicroelectronics/l78l33acz/ic-v-reg-3-3v/dp/1467768

Thanks for that suggestion. I’ll look into it. Still just in the planning stages for the power replacement, and exploring all options

 

[alasdairmp]

If you get the parts - choose the TO-92 case for the regulator. The capacitor types are not critical.

 

[mangoelectrics]

As @Moley said I would just get one of these: Aliexpress.com
Ive purchased numerous of them before. Can't get anything better for the price and SO easy to set up.
You will only need a multimeter.

Hope this helps!

 

[mainline]

I am attempting to build a garage door remote for use on my motorcycle using a small remote and a handlebar mounted momentary push button switch. What I would like to do is remove the CR2032 battery and use a stepdown converter to wire directly into the motorcycle’s 12VDC system as I’ll be putting the remote circuit board inside the headlight housing. Is this possible and, if so, is there anything I should be concerned with such as heat or anything, and what protection can or should I add?

Appreciate the help and suggestions

Remote controls usually last a very long time i wouldnt have thought it worth the effort in doing.
If you are intent then the l78 is the easiest route to take as it will probably fit in the the space of the removed battery.

 

[brianmoooore]

Remote controls usually last a very long time i wouldnt have thought it worth the effort in doing.

Agree. I have a r/c for my garage roller shutter mounted on the dash of my car with a double sided sticky pad. It has a 12V battery (1/2 AAA?), and when I fitted it in 2012, I intended to discard the battery and connect to the car supply, when I found the time. This never happened, and I've had to replace the battery once, a few years ago.

 

[EalingBadger]

A buck converter does sound rather over the top for such an application.

A zener diode and a resistor would do just fine.

Cheaper, and much smaller as an assembly to fit inside the bike headlamp.

Also, less to go wrong!

You'll want to determine the current draw of the device in order to size the resistor and power rating of the zener accordingly but it won't be much if it normally runs off a CR2032.

 

[mainline]

A buck converter does sound rather over the top for such an application.

A zener diode and a resistor would do just fine.

Cheaper, and much smaller as an assembly to fit inside the bike headlamp.

Also, less to go wrong!

You'll want to determine the current draw of the device in order to size the resistor and power rating of the zener accordingly but it won't be much if it normally runs off a CR2032.

using the ic will work far better than a zener and is easier to fit.

 

[EalingBadger]

using the ic will work far better than a zener and is easier to fit.

Well I guess we are just going to have to agree to disagree on both of those counts then.

 

[mainline]

Well I guess we are just going to have to agree to disagree on both of those counts then.

I dont really know what there is to disagree about.

The L78L series employ internal current limiting and thermal shutdown.
making them essentially indestructible. they can deliver up to 100 mA output current. They are intended as fixed voltage regulators in a wide range of applications including local or on-card regulation
for elimination of noise and distribution problems associated with single-point
regulation.
In addition, they can be used with power pass elements to make high-
current voltage regulators. The L78L series used as Zener diode/resistor combination
replacement, offers improvement along with lower quiescent current and lower
noise.