Anybody

[tsweat]

Has anybody tried building their own relay for a "one touch cab-top" function?

I know the following company has done it Bahn Tech Autotop, but it does not seem that it would be too terribly difficult to make your own.

Any thoughts on how to go about it?

[Scouser]

I have looked into this in a lot of detail.

It is not simply a relay. You need an electronic timer (probably using a LM555 or something similar) to close the relay. And the timer would have to be adjustable or preset when made. This is probably why

BahnTech ask you to specify the time it takes in seconds

to put your hood up. There are also timeout and connection send

sensors required for when the operation completes of if it fails.

Basically you need a switch triggered interlocked monostable timer that

is triggered when you push the switch, holds until the top opens/closes,

then times out when detecting a current release as the operation completes. The interlock circuit uses two LM555 timers, one for the open and one for the close operation. Each car's hood will open/close

at different times (even microseconds difference) so both timers will

have to be variable via their threshhold circuitry (pin 6 on the timer).

The interlocked cicuitry is also used so that each timer can be safly

interrupted. I.e., you click the switch then would also want to be able

to click it again to stop/pause the operation...or even reverse it.

As you can see it isn't as simple as just a relay.

As I said I will work on this some day......

Still having said that I have put a cuircit diag together but just haven't

got around to impementing it yet.

Edited September 27, 2004 by Scouser

[tsweat]

Thanks for the insight. I was not sure if you could purchase on the open market a timed relay, etc. Let me know if you get around to the implementation stage anytime soon. :)

I may break down and spend the $99 and not worry with the hassle...

[HenryV]

As scouser points out, a simple "timed" relay does not suffice. The controls are a little more complicated. Essentially, it works analogous to the window controls (stop/start/auto/manual), with speed, latch and other controls added.

SmartTOP (SmartTop Webpage) has a nifty relay replacement solution that just plugs in and has everything integrated. They are the most expensive solution at 228 Euro (185 Euro in group buys).

Bahntech is the cheapest solution ($145) and does it with a custom printed circuit board that "hangs" between the dash buttons and the actual inputs to the relays. For it to work as desired you need to plug in the speed sensor wire and perform the two relay hacks (disable handbrake and speed signal).

I have the Bahntech in the 986 and am quite satisfied with it. Roll-your-own is doable, but probably not worth the roughly extra $100 you might be able to save. If you consider going the smartTop "clean" approach, be aware that just the relay replacement switch is $70 for starters :(

I don't think the Bahntech unit is "timed", but rather it uses the signal from the metal hood cover when it closes (same signal in "top up" and "top down" position) to signal the end of the cycle. This would allow for simplier electronics (not car dependent). But I may be wrong on this.

Now, if Porsche is using the SmartTOP in the 997s, the price might drop somewhat. Anybody knows about this?

[Loren]

As scouser points out, a simple "timed" relay does not suffice. The controls are a little more complicated. Essentially, it works analogous to the window controls (stop/start/auto/manual), with speed, latch and other controls added.

SmartTOP (SmartTop Webpage) has a nifty relay replacement solution that just plugs in and has everything integrated. They are the most expensive solution at 228 Euro (185 Euro in group buys).

Bahntech is the cheapest solution ($145) and does it with a custom printed circuit board that "hangs" between the dash buttons and the actual inputs to the relays. For it to work as desired you need to plug in the speed sensor wire and perform the two relay hacks (disable handbrake and speed signal).

I have the Bahntech in the 986 and am quite satisfied with it. Roll-your-own is doable, but probably not worth the roughly extra $100 you might be able to save. If you consider going the smartTop "clean" approach, be aware that just the relay replacement switch is $70 for starters  :( 

I don't think the Bahntech unit is "timed", but rather it uses the signal from the metal hood cover when it closes (same signal in "top up" and "top down" position) to signal the end of the cycle. This would allow for simplier electronics (not car dependent). But I may be wrong on this.

Now, if Porsche is using the SmartTOP in the 997s, the price might drop somewhat. Anybody knows about this?

I believe that SmartTop (as well as the Bahntech solution) are only for Boxsters. The 996 top control is much more complicated - it does not use a relay but a separate control box.

[Scouser]

...<snip>....

I don't think the Bahntech unit is "timed", but rather it uses the signal from the metal hood cover when it closes (same signal in "top up" and "top down" position) to signal the end of the cycle. This would allow for simplier electronics (not car dependent). But I may be wrong on this.....<snip>....

<{POST_SNAPBACK}>

The reason I am fearly certain it is timed is because at one time I

intended to purchase a Bahntech unit and contacted them. I was heading

out to CA and intended to pick it up. Anyway, the guy at Bahntech asked me

to time how long it took my hood to open and close with the engine running.

He then said to report this data back to him so that he could program

the unit and have it ready for me.

I agree that it's probably better to spend the $100 and buy the unit. But I am

a bit of an electronics geek so the idea of a little project tickles my fancy ;)

[larez2]

Where did you see it for $99, the link says it $149. It think it's worth $99 for that convienence.

Couldn't a 3 position rocker switch just be installed in the place of the existing switch? Click in one direction to open, click in the opposite to close and then the center position is neither. You would just need to be sure to switch it back to center after opening or closing or you could risk burning something out. Then no need for timers etc. Does that sound feasable/practical, or unwise?

Larez2

[HenryV]

I believe that SmartTop (as well as the Bahntech solution) are only for Boxsters. The 996 top control is much more complicated - it does not use a relay but a separate control box.

<{POST_SNAPBACK}>

-- HV: Both claim to support the 996, albeit SmartTOP only since this(!) month:Translated SmartTOP feedback page

Bahntech for some time: Bahntech claims both 986 and 996 support

... Anyway, the guy at Bahntech asked me to time how long it took my hood to open and close with the engine running...

<{POST_SNAPBACK}>

-- HV: Must be a 996 thing - they asked no such question for my 986 order.

Where did you see it for $99, the link says it $149. It think it's worth $99 for that convienence.

<{POST_SNAPBACK}>

-- HV: It's $99 above what you would spent in parts - estimated at $50. So $145 out-of-pocket plus tax/S&H.

Henry

[tsweat]

A few guys over on 6-speed have installed it with success in their 996's. I am going to give it a shot and will let you guys know how it works.

[Tool Pants]

Before Bahntech there was TouchTop, invented by local 2001 Boxster owner Ed Brakus. Ed tried his test version on my 1997 Boxster years ago because he wanted to see if there was a difference between the years.

TouchTop was a simple timer. I think Ed said it was set to 60 seconds for the Boxster and 996. A Boxster only need 12 seconds to open or close the top, and the 996 Cab takes longer. So on a Boxster the electronic timer would contine to run even after the trop stopped moving. It was originally $100, then $200. Ed sold them for a few years then stopped.

[wilhelmy-it]

Hi all,

just a quick announcement, all smartTOP modules are now available in the Unites States via the new subsidiary Wilhelmy-IT Inc. in Kansas. Direct order possible. We offer smartTOP modules now for all Boxster AND 911 (996) models. All smartTOP modules are Plug-n-Play with NO soldering, cutting wires or "relay hack". All modules implement our safe speed control and offer One-Touch operation while driving. For the new (2003+) models smartTOP offers functions like closing the windows with the key remote and enabling the rear windows when the roof is open. All information (in english) can be found on our website "www.smarttop.de"

[Guest]

Hi all,

just a quick announcement, all smartTOP modules are now available in the Unites States via the new subsidiary Wilhelmy-IT Inc. in Kansas. Direct order possible. We offer smartTOP modules now for all Boxster AND 911 (996) models. All smartTOP modules are Plug-n-Play with NO soldering, cutting wires or "relay hack". All modules implement our safe speed control and offer One-Touch operation while driving. For the new (2003+) models smartTOP offers functions like closing the windows with the key remote and enabling the rear windows when the roof is open. All information (in english) can be found on our website "www.smarttop.de"

<{POST_SNAPBACK}>

Since the product can operate on a 2002 while moving does that mean the emergency brake lever does not have to be engaged at all?? :)

[wilhelmy-it]

Since the product can operate on a 2002 while moving does that mean the emergency brake lever does not have to be engaged at all??  :)

<{POST_SNAPBACK}>

No emergency brake necessary. The product continuously monitors your speed and only lets you operate the roof at safe speeds.

[Guest]

On a 2002 TipS requiements include putting gear in park and engaging handbrake+ holding switch in order to operate the top. Just to make sure, your product will negate all of those requirements. TIA :)

[wilhelmy-it]

On a 2002 TipS requiements include putting gear in park and engaging handbrake+ holding switch  in order to operate the top.  Just to make sure, your product will negate all of those requirements.  TIA :)

<{POST_SNAPBACK}>

The smartTOP module directly connects to the main control device and sits "between all necessary signals". So when you drive slower than the maximum allowed roof-operation speed it will work fine. No need to put the gear in park or pull the handbrake. The installation in reversible and only takes about 5-10 min for an unexperienced person using our installation manual. It takes 2-5 min if you ever had the carpet lifted and know how to remove the 4 plastic plugs. The rest is just pulling a connector and inserting the smartTOP.

If you're unsure just give it a try. We give a 14 day satisfaction guarantee and never got a single module back :-)