Tach Time

Has anyone found an instrument that will read a pulse and record Tach time? Aircraft currently has a Hobbs and the Vans tach with no tach timer.

Was going to cobble something together with an Arduino to read the pulses from a pmag or the vans transducer. Before I did that, I wanted to see if someone already invented the wheel aside from going to a new tach.

I have been flying with friends a lot and cruising at 172 speeds.

You say you want to add an instrument, but not change the tach? - Curious why?
I replaced my Tach with an MGL RPM-1 and love it! I feed it with two tach signals - one from the magneto, and one from the old Vans gauge, which is mechanically slaved to the engine. I can choose which one I want to use, but always use the tach. signal. I did not want to give up my Vans gauge because it matched the rest of my panel, and I did not think I would like a digital tach VS the analog tach. What was I thinking?? This gauge gives me a digital RPM read-out and an analog indication with a settable yellow and red range. It has a mag check feature that tells me the exact mag drop left and right. It also has maintenance alarms to remind me when my oil change is coming up. Very visible and easy to read.
I tend to run lower RPM's and see about a 10% lower tach time VS my hobbs meter.

PS – if you are flying slower you should consider using a lead scavenger to keep your engine clean. Lead deposits build up more at lower power settings.