Gated clock pulses

[DSG]

I would like to produce short bursts of clock pulses (about 6 or 8 pulses of a 40KHz clock every tenth of a second). I know how to use a 555 to produce a gate pulse every tenth of a second that is the correct duration, but how would I synchronize the circuit so there is not a transition in the middle of a clock pulse?

 

[Nigel Goodwin]

Essentially you don't, and why would it matter?.

Best solution is to program a PIC to do it, an 8 pin PIC is the same size as single 555, and will do it much more accurately with less components.

Presumably you're wanting to generate IR remote pulses?.

 

[DSG]

Actually it is for an ultrasonic transmitter. Will a PIC generate accurately timed 40 KHz pulses to properly resonate the transmitter? One cycle makes a difference of about 8.6 mm travel time. I would like a consistent measurement which means I would like a complete pulse at the beginning of the pulse stream.

The other consideration is that the circuit runs off of a 9V battery and I need the battery to last as long as possible. The pulses are not always on, so I need as low of a power draw as possible in its quiescent state.

DSG

 

[Nigel Goodwin]

Actually it is for an ultrasonic transmitter. Will a PIC generate accurately timed 40 KHz pulses to properly resonate the transmitter? One cycle makes a difference of about 8.6 mm travel time. I would like a consistent measurement which means I would like a complete pulse at the beginning of the pulse stream.

Same thing, IR copied the existing frequency from ultrasonic remotes.

A PIC will generate far MORE accurate 40KHz pulses than a 555.

The other consideration is that the circuit runs off of a 9V battery and I need the battery to last as long as possible. The pulses are not always on, so I need as low of a power draw as possible in its quiescent state.

PIC's are also EXTREMELY low consumption devices, with various included features for further reducing current drain.

 

[DSG]

PIC it is then. Thanks for the help.