Hi Joe, My problem is in trying to get the LED to have three quick successions=20 with increasing frequency and then off. If the on pulses were a water,=20 it would be like throwing a stone onto a calm pond and seeing the=20 ripples start as one ripple and then quickly followed by a second ripple=20 and slightly more quickly followed by a third and then calm until the=20 next stone is thrown. I'll have a theoretical play with your idea. Colin -- colin@btech-online.co.uk Web presence: www.btech-online.co.uk Hosted by: www.justhost.com.au This email is to be considered private if addressed to a named =20 individual or Personnel Department, and public if addressed to a blog, =20 forum or news article. __________________________________ Sent from eM Client | www.emclient.com On 04/04/2017 09:09:51, "IVP" wrote: >> a 555 for the osc and something like a 4017 for a counter > >Looking at the police helicopter last night (over someone else's >house of course) the 'on' is a lot shorter than the 'off'. Maybe there >needs to be a one-shot (eg 1/2 4001) between the logic and LED >or a couple of cascade 4017s so you can be working with 2x the >clock speed in 20ths of a cycle rather than 10ths > >Joe > > >----- >No virus found in this message. >Checked by AVG - www.avg.com >Version: 2016.0.8012 / Virus Database: 4769/14231 - Release Date:=20 >04/03/17 > >-- >http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .