Hot Lap Timer on switched 12V

PCA7GGR · 09-01-2004, 04:05 PM

Anyone out there modify their Hot Lap Timer to operate on their car's switched 12v?

When I had the timer with the large display and I left the timer on overnight, it was pretty easy to replace the battery. Now that I have the small display, I just know its just a matter of time (punny, punny) before I leave this one on - replacing the battery on the receiver is a pain.

Thanks

John Rogers · 09-01-2004, 09:03 PM

If the Hot Lap has an external 12 volt supply, then it can be hard wired in. I have my race transponder wired that way, race camera and cool suit. The cool suit is wired so there is power to the switch if the key is off, so I can pump the cold water when in pit lane and the engine is off. There are several extra lugs on any of the Porsche fuse boxes so it can be connected. If you need a plug, electronic supply stores sell them and make sure to put in a fuse just in case. Good luck

PCA7GGR · 09-01-2004, 09:18 PM

The Hot Lap is powered by a 9vt dry cell battery.

widebody911 · widebody911's Garage

Is it just me, or is the Hot Lap timer absolute junk from an usability/features/engineering standpoint?

For one, there's no reason the display unit has to be so huge. Second, since it's designed to be used in a car, and is generally kept in the car, why do they still use 9v batteries?

It's like a Radio Shack breadboard project that never evolved once they got the first one working.

John Rogers · 09-02-2004, 09:40 AM

Well, speaking of Radio Shack, they do sell an adjustable DC converter that outputs different voltages such as 9 or 6 or 12 volts. You would have to add a plug to the hot lap in place of the batt connection and then wire the DC adapter onto the fuse panel. I think it is doable. Good luck

Dleong · 09-04-2004, 02:20 AM

Serg,

I have one of these wired into my car. Remind me to show it to you. jim P. also has one.

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=273-1818

PCA7GGR · 09-04-2004, 06:01 AM

Dave,

I would love to see it. Auto-x next Saturday at Alameda?

Jack Olsen · 09-04-2004, 10:12 AM

Quote:

Originally posted by widebody911
Is it just me, or is the Hot Lap timer absolute junk from an usability/features/engineering standpoint?

For one, there's no reason the display unit has to be so huge. Second, since it's designed to be used in a car, and is generally kept in the car, why do they still use 9v batteries?

It's like a Radio Shack breadboard project that never evolved once they got the first one working.

I believe Longacre bought it from the guys who actually developed it, and then never did anything with it.

I have intermittent problems with mine that drive me crazy.

Next time around, I may get one of these:

http://www.aim-sportline.com/auto/laptimer.htm

http://www.cc-2000.com/xtracing/en/ultra-lap/index.html

It's nice to know there will be a transmitter already set up, most of the time, but the other Hotlap-associated headaches are beginning to outweigh that.

PCA7GGR · 09-05-2004, 07:27 AM

Dave and John,

I have seen the Radio Shack converter. I know that your can buy this one and then gut it for just the circuitry but I am hoping to find a more compact solution.

TMH · 09-07-2004, 06:24 AM

Quote:

Originally posted by PCA7GGR
Dave and John,

I have seen the Radio Shack converter. I know that your can buy this one and then gut it for just the circuitry but I am hoping to find a more compact solution.

I actually just did this over the weekend. I just got the 12v-9v DC/DC convertor, not the multi one. After you take the plug unit apart and hard-wire the input leads to it, it does indeed make a rather compact solution. And it puts out 1 amp, so I should not have to worry about any fluctuations which might impact the accuracy of the Hot Lap, as I have seen on other threads.

Tom

PCA7GGR · 09-07-2004, 06:45 AM

Tom,

Great. Now, is it a Radio Shack part, if so do you have the part number? Aslo, any pics on how you connected it to the timer? Thanks

TMH · 09-07-2004, 10:44 AM

Sergio,

It is Rat Shack Catalog #: 273-1863. I unscrewed the the plastic nut off the tip, and pulled the guts out of the case. Then I desoldered the wire from the negative input, and the clip from the positive input, and just soldered in negative and positive wires. I clipped off the LED, and then the whole thing can be covered with heat-shrink tubing. Makes a small package.

Since this is a track-only car, I have some things available which are not normally there in street cars. In my case, I have switchable, fused 12V which I use for power to my video camera. I connected this 9V adapter inlet to this bus bar, and just zip-tied the shrink-wrapped unit in place to some existing wiring bundles "behind the dash" (in the front bonnet). There was already a hole in my dash where the PO had run some sort of wire, and it came out very close to where my HotLap is mounted (where the stereo used to be).

I wanted to go back to using 9V alkaline batteries with the HotLap if my new solution was not reliable, so I didn't want to cut off the battery connector. Therefore I got one of these: Catalog #: 270-324. This allowed me to just plug in the new output from the 12vdc/9vdc convertor, but go back to alkalines if I ever wanted to. I then taped the connection together so it would not vibrate loose. To get the wire into the battery compartment of the HotLap, I just used a Dremel tool to cut a slot into the battery "door". It snaps right back into place, but the wire can now come out right through the door of the battery compartment.

All pretty simple, and took less than an hour.

Tom

PCA7GGR · 09-07-2004, 03:13 PM

Tom,

Thanks for the explanation - that should do it for my application.

dad911 · 09-07-2004, 05:11 PM

For those that can solder, you can make a circuit like this for about $3: http://www.zen22142.zen.co.uk/Circuits/Power/9v2a.htm

PCA7GGR · 10-16-2004, 03:23 PM

Thanks to everyones excellent input, I finally went to Rat Shack and bought the following:

The parts included:
- A switchable rate converter (3-6-9-12vt)
- A 9vt battery connector
- A 6 foot extension
As was suggested, I opened up the converter cigarette lighter plug, cut of the lighter plug off and hooked up the red wire to one of the car's switched hot wire and grounded the black wire to the tub.

I then cut a notch in the metal housing of the Hot Lap receiver, plugged in the 9vt battery terminal and used the 6 ft "patch" cord between the battery hookup and the converter.

Cost was under $25 and it took about an hour to rig up. Thanks again