Digital tacho's?

Could someone please point me in the direction of where i can purchase a digital 12v tacho, when towing a transporter trailer behind a car transporter (rated to 3500kg) it of course takes me over the 3500kg limit before i legaly need a tacho, appreciate the help thanks guys

edit: preferably one that can be run in addition to standard speedo so i only have to run it when towing, cheers

Click here to go to the VOSA website

and click on

Regional Tachograph List of Digital Centres
A region by region list of companies that can fit Tachographs.

this downloads a excel file

Thanks, something i can fit myself or do i need to have it fitted by an authorised outlet?

Tachographs (analogue or digital) must be fitted and calibrated by an approved Tachograph Centre - the ones on the list Denis F provided the link for. Be careful, not all tacho centres can fit digital.
All the digital units I’ve seen use a ‘slave speedo’ as the display of the tacho is not within the drivers’ immediate field of view when looking at the road ahead. As the Vehicle Unit provides the speed signal for the speedo, the tacho will be ‘on’ the whole time.
You also need to ensure that the vehicle has a gearbox on it suitable for a digital tacho. Many light goods vehicle and 4x4’s apparently cannot have a digital tacho fitted, if they were registered after 01/05/2006 they cannot be used on EC controlled journies.

This thread may interest you

http://trucknetuk.com/phpBB2/viewtopic.php?t=15682