Hardwiring garage remote

[Thor]

Hi Guys,

Batteries go flat in the garage/gate remote like nothing else.
is hardwiring the remote into the car's 12v a bad thing? i'd hope it would boost the range
seriously though, is it as simple as a resistor inline then connected to the remote control's battery +/- terminals?

Cheers

[-Scott-]

NO!

Hardwiring is not a bad thing, but DO NOT go the "resistor" route. Resistors only drop voltage when there's a current. What happens when there's no current? If you're lucky, it may not be an issue, but it's a cheap and nasty option. If you're unlucky, you'll be up for a new remote.

Remotes don't draw enough current for the current source to make a difference to the range. But, if you want to hardwire it, use a voltage regulator.

What battery voltage does your remote use?

Scott

[Thor]

ah ha i see, thanks for the reply scott.
the remote uses two 3v batts stacked one on the other.
so what's on the shopping list?

[-Scott-]

A 7805 voltage regulator. It will drop your car voltage to around 5V, which should be adequate for a remote - if you want to get fussy, you could bump it up to 6V, but it would make it more complicated.

A three terminal (TO-220 or TO-92) package. One pin is voltage in (12V), one pin is ground, the third pin is voltage out.

If you're with me so far, Google for "7805" for which pin is which. If you need more info, post again.

Or wait for Gary to give you better help?

Scott

[DamTriton]

A 7805 voltage regulator. It will drop your car voltage to around 5V, which should be adequate for a remote - if you want to get fussy, you could bump it up to 6V, but it would make it more complicated.

A three terminal (TO-220 or TO-92) package. One pin is voltage in (12V), one pin is ground, the third pin is voltage out.

If you're with me so far, Google for "7805" for which pin is which. If you need more info, post again.

Or wait for Gary to give you better help?

Scott

Since when did I become a friggin' expert

A really obvious question, but have you changed the batteries in the remote lately??????? I went from a PITA at point blank range to being able to hit the button early enough to not have to stop and wait for the gates to open (300-400m) after having similar issues.

Building it in is not really going to help with the Tx/Rx distance, and in fact may hurt the distance due to the shielding the metalwork of the car provides.

Velcro the transmitter to the back of the rearview mirror or visor (or on top of it if you have room) so you have "line of sight" to the reciever.

Yeah, sometimes the easiest approach is the most effective............

Batteries go flat in the garage/gate remote like nothing else.

You keep the remote in your pocket
Other keys/mobile phone/other crap hitting the button all the time

My batteries in the remote I left in the car lasted ~3 years before they needed changing.

[Thor]

Hmm i see.
The batts work well when new but they/range dies too quickly.
I'll have a think about this one as as you say the car may effect the signal.etc
Maybe a rainy day

cheers scott/gaz

[Dooley]

Just thought I'd say Scott, there is no need to use a 7805 or any other fixed voltage regulators in that series. Use the 317/337 it is easy to get, cheap,voltage can be changed and adjusted easily and you can choose whatever voltage you want.

You'd think there'd be some benefits of going fixed but if you can bothered adding in a big tantalum and a back emf diode, it has significantly lower noise than the fixed voltage version and pretty much all other specs are the same. Although you do have to put 2 resistors in, big deal.

[-Scott-]

Yes, you can also bump up the 7805 voltage to a higher voltage if you really want - if you know how.

A 7805 regulator, all by itself, should do what he wants. It doesn't come any simpler, which was why I suggested it.

[F'n_Rover]

go a 78L05 - should be able to fit it all in the battery compartment of the fob.

[Dooley]

True. Keeping it simple is probably a good idea in this case.

Have heard of being able to increase it but never bothered trying.

Just personally I'd rather have a heap of 317/337s in the parts bin, rather than a few of each fixed one.

[DamTriton]

Remember that there will be a parasitic current drain when using the regulators, granted, not that much, but possibly enough to flatten a battery if left for a month or two.

As a whole, still not in favour of the idea, it is whare it is that is the problem (usually dangling on your keyring, screened by the body of the car), not how strong the signal is (works well when new batteries fitted).
Velcro it to the sun visor...