I'm trying to use a Basic Stamp (BS2) to count pulses from a harley sportster ignition. I'm taking the pulses from the same same point that feeds the tachometer, which is the low side of the ignition coil (the output from the electronic ignition). The pulses are first fed into a voltage divider which cuts the volts down to about 4 volts. Resulting in a pulsating dc voltage in the range of 4 volts. The pulsating dc is fed into a Schmitt trigger which cleans up the pulses, then these pulses are sent to the BS2. The BS2 is programmed with a 'COUNT' command to count the pulses. It counts them, but with numbers that are three, sometimes four, times what they should be. I rev the engine and use the tachometer to set the engine speed to certain RPMs.
I've also used, inplace of a Schmitt trigger, a monostable multivibrator and get no counts at all.
However, I can do this operation in house using either the Schmitt or the monostable MV and get proper results.
I use a sound recorder to 'capture' the pulses from the sportster ignition, bring that ckt. to the BS2 in house and using either the Schmitt or the monostable MV and get proper counts.
The Schmitt and the monostable MV are made using 555 counter chips.
Any ideas as to why counts are off when pulses are taken directly from the sportster ignition, but ok when using a sound recorder to 'capture' the pulses first?
I suppose it would be best to include schematics, if needed, I'll try to do that later. Right now its quite late at night.
P.O'T
I've also used, inplace of a Schmitt trigger, a monostable multivibrator and get no counts at all.
However, I can do this operation in house using either the Schmitt or the monostable MV and get proper results.
I use a sound recorder to 'capture' the pulses from the sportster ignition, bring that ckt. to the BS2 in house and using either the Schmitt or the monostable MV and get proper counts.
The Schmitt and the monostable MV are made using 555 counter chips.
Any ideas as to why counts are off when pulses are taken directly from the sportster ignition, but ok when using a sound recorder to 'capture' the pulses first?
I suppose it would be best to include schematics, if needed, I'll try to do that later. Right now its quite late at night.
P.O'T