Hidden tachometer and gauges

Now you see them:

Now you don't:

 


1964 Buicks have a pretty large ash tray right under the radio, in a very visible and convenient spot to look at. After seeing others make such modifications to this area such as radios and large round gauges, I was motivated to add some hidden gauges. All parts are slide in, so no damage was done to the car and the original ash tray could be replaced.


I started with a Supro LED tach, and LED triple gauge cluster. They discontinued these in the 90s, but it was just the look I was wanting. However, when I first started off, I couldn't get the triple gauge hidden.

I originally had the tach mounted in the ash tray sans its case and the gauges surface mounted to where the ash tray handle was, and the ash tray handle mounted to the gauges.

The gauges come apart:

 


Notice each module has a separate logic board and LED board. In the modified installation, the logic board were remotely mounted so just the LED driver boards were mounted in the ash tray.


I removed every individual LED, painted everything but their fronts black so they wouldn't bleed to each other, and soldered them to the circuit board. The final design has three more illumination lights at the bottom.


Here is the completed ashtray unit. The two LED driver boards are at the top and bottom, with plastic secured to them with double sided tape for insulation. Due to the tight dimensions of the ash tray opening, a standard case wouldn't work. They are soldered to the LED circuit board, shown to the right. A DB25 carries the remote signals from the logic boards to the driver boards.



This is the inside of the logic board enclosure. Once again, a custom plastic case. The DB25 connects to the ashtray assembly, and the white cable is a multi-core cable that carries the voltages from the sensors.


Here are the two hooked together. The gray enclosure was Velcroed in the dash under the glovebox opening, hidden from view.


Here it is fully illuminated.

 


Finished product. The mask around the LEDs was printed on a transparency backwards so that the toner is on the side facing away from the gauges for an even look.