On 04/04/2017 05:15:24, "Dave Lagzdin" wrote: >and I forget the part >number of the other one), has an oscillator and should find suitable=20 >outputs from the dividers I can't recall if that was a 74xx or 40xx part, I had a quick look=20 online but couldn't find it. If only I still had my TTL/CMOS logic=20 books. This weekend I'll go through my old magazine compendium books from the=20 70s and 80s they may well give my memory a jog. >-- 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 05:15:24, "Dave Lagzdin" wrote: >I'd probably try playing with an old cmos 4060 ( >D > >On 1 April 2017 at 20:30, CDB wrote: > >> I was chatting with someone from work the other day and the=20 >>conversation >> turned to them wanting to put an LED on their quadcopter which had a >> strobing light similar to the navigation light on an aircraft, the=20 >>one >> that appears to make quick succession flashes that increase in=20 >>frequency >> making it look like one flash-pause pause next flash - pause -flash. >> This would be easy to do with three LEDs in parallell, light LED 1=20 >>then >> LEDs 1 and 2, then LEDs 1,2,3 >> >> This got me thinking on how to hypothetically come up with a circuit. >> >> The criteria would be: >> >> No uP to be used. >> Vcc =3D 5V >> One white high brightness LED >> Flash rate unsure but I suspect around 1 to 2 Hz >> As few components as possible >> Small footprint. >> >> Now as I tend to come up with complicated ideas and then work=20 >>backwards >> to simpler ones, I'm looking for comments and other ideas on what I=20 >>have >> thunked up so far. >> >> 1. The obsolete LM3909 might fit the bill (still available on Ebay) >> except I need 3 flashes per period >> =20 >>(https://www.digchip.com/datasheets/parts/datasheet/321/LM3909-pdf.php) >> >> 2. CD4017/74LS90 decade counter + CD4093/74LS00 NAND gates for >> oscillator + 1 74LVC1G27 single triple input OR gate chip connecting=20 >>the >> decade counter outputs to the LED. >> >> 3. 74LS196 decade counter + CD4046 PLL driven by unijunction >> transistor the idea being the frequency will change with the sawtooth >> pattern and hence the light pattern will change. >> >> 4. CD4048 dual retriggable monostable + 555 as oscillator then OR the >> two outputs together. >> >> 5 Pulse generator using an 74LS10 quad NAND gate + 555 as a clock >> generator and OR gate at the two pulse outputs driving the LED. >> >> I've just thought, I suppose I could use a dual 555 timer + driver >> transistor. >> >> I'm sure back in the 80s there were special one chip flasher chips=20 >>aimed >> at toys which did exactly what this circuit needs, but I threw my=20 >>lovely >> paper based Maplins catalogue out years ago (1999 to be precise). >> >> Comments welcome. >> >> 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 >> individual or Personnel Department, and public if addressed to a=20 >>blog, >> forum or news article. >> >> >> >> __________________________________ >> Sent from eM Client | www.emclient.com >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >-- >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 .