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[Skimmer Fan]

Hi.
I have been looking for a timer to run a crane on a puffer. I have got to the stage where I can do all the actions but I can only repeat it with a small delay before the next sequence starts. The ones I have found only give short delays. I want to use it at displays but would like it to work automaticaly every 15 minutes. Hope I have explained this right.
12 volt supply and small enough to fit in 1/32 models hold.

[inertia]

I built one of these a while ago and I'm pretty sure that by changing the value of the electrolytic capacitor (as per the instructions) you can obtain up to 60 minutes delay (which is adjustable). http://www.maplin.co.uk/p/mk111-adjustable-timer-kit-with-relay-output-vt27e  You should note that the relay only remains on for a maximum of five seconds.
DM

[Skimmer Fan]

Inertia
I have looked at this one but when it said 2.5 to 60 seconds delay I thought that was all you could get it to do. Thanks for that I will get one today. I only want to activate the control board so 5 seconds is well long enough.
Thanks for that I can follow soldering diagrams but componants as they say are a black art.
Regards
Skimmer Fan

[malcolmfrary]

The kit manufacturers drawing/building instructions here - http://www.velleman.eu/downloads/0/minikits/manuals/manual_mk111.pdf -
it is recommended that the circuit should be run on 12 volts.  Since it is based on a 555 timer chip, the actual circuit should be happy on anything from 3 to 15 volts, but the relay is probably a 12 volt type. 
If the urge is felt for a higher value capacitor to give a longer delay, look for a Tantalum Bead type.  These tend to be more stable.  Since the same capacitor provides the timing both for the delay and switching time, both will be affected.  The good news there is that there is a separate adjustment for each.

[grendel]

the timing circuit is usually based on a resistor/ capacitor combination (via the charging / discharging of the capacitor), usually the variation is controlled by a variable resistance value, but as mentioned above if you increase the capacitance you can also raise the time taken for the delay, this will generally give a longer time, but for a specific time it will be more fiddly to set.
Grendel

[Skimmer Fan]

malcolmfrary / grendel

 100µF 10V Tantalum Bead Capacitor
 33µF 10V Tantalum Bead Capacitor
These are the only Tantalum Bead Capacitors I can find in Maplin online. I have attached the circuit diagram and marked c2 which is the one I think I change.
I intend to solder a flying lead in place of the capacitor so I can change the components until  get the right delay

[Skimmer Fan]

Sorry Inertia I forgot to include you

[TheLongBuild]

malcolmfrary / grendel

 100µF 10V Tantalum Bead Capacitor
 33µF 10V Tantalum Bead Capacitor
These are the only Tantalum Bead Capacitors I can find in Maplin online. I have attached the circuit diagram and marked c2 which is the one I think I change.
I intend to solder a flying lead in place of the capacitor so I can change the components until  get the right delay

Blimey, I don't come up to the hut for a couple of Sundays and this is what you get up to !!, I' m scared to even enter the building now ..

[Skimmer Fan]

Well there you go part timer you missed the sound system frying last Wednesday waiting for a big boom now if I gat the next thing wrong. I think next weekend its electro magnets.

[TheLongBuild]

Well there you go part timer you missed the sound system frying last Wednesday waiting for a big boom now if I gat the next thing wrong. I think next weekend its electro magnets.

Ummm.. I think a surprise , spot inspection might be due on Sunday..  May even bring a boat 

[TheLongBuild]

malcolmfrary / grendel

 I intend to solder a flying lead in place of the capacitor so I can change the components until  get the right delay

Do what !!

I am expecting great things from this timer, must admit when ever I try any soldering on electronics the results are a bit dodgy to say the least.

[malcolmfrary]

Its C3 that does the timing, both for the delay (charging) and for the pulse length (discharging via the other path).  The lack of higher value tanalum beads at Maplin is a tad disappointing (they probably noticed that they were useful, and therefore followed their long standing policy of ditching them), but I was probably just being picky.  Regular radial cans are a lot better than they used to be, and the actual timing is not hyper critical.
Upping the value will increase the range of timings available, but note that the increase will likely not be linear - the input sense of the 555 does take some current which does affect the timing somewhat.  When designing circuits with a long timing, it was common to use the CMOS version, or use a short repeating pulse supply and count the pulses.  For what is wanted, this would be overkill.  Anybody into programming PICs would probably laugh his socks off, then spend the next 40 seconds or so writing a routine to do that exact job.

[Netleyned]

Why bother with Craplins for components when there are company's
like Farnells and RS Components out there.
I gave up with Napkins  (Predictive Text  )
and quite apt , as I got fed up with kids trying to tell me
facts about electronics when I have spent all my working
life involved in the aforesaid.
Both the above have served me well over the years and I
have had good service from both company's.

Ned

[inertia]

Ned - The slight wee probby with those suppliers (and JPR and Rapid) is that they have minimum values for on-line orders. Either that or you incur a hefty "handling fee", which might mean paying £0.10 for a capacitor and £5.95 for 'shipping'! Agreed that Maplin are next to useless - more of a toy shop these days.

Skimmer - if you want to PM me your postal address I can send you a 220uF x 16v electrolytic cap which should do the job nicely. 

DM

[NFMike]

I use Rapid a lot. They sort of fall between Maplins and Farnell/RS - better stock than Maplins, easier to use than the other two (my personal opinion).
That said for odd low cost components I often use ebay as you can often get them with free postage which saves a lot (Rapid is £3.99 p&p for smaller orders; <£30 IIRC).


(I've crossed posts with Inertia, but I think the above is still valid)

[Netleyned]

That's put me in my place

I bought from most of these company's for repair and
R &D and the lowest invoice would have been 50 squids or more
Paid by the Company
Anything I needed privately was added on with the Owners approval
and I paid for my bits vat free 

Ned

[inertia]

Plague - I may have been guilty of exaggeration for the sake of illustration - it's a habit I've been trying to get rid of for about a hundred years. Try JPR if you buy a lot of passives or "stock" semiconductors - you can save yourself a lot of money. http://www.jprelec.co.uk/ Their minimum order value is £30 excl VAT.
Ned - Nice one if you can get it, mate. Since flogging ACTion I'm hard-pressed to put together a minimum order. 
Dave M

[NFMike]

Plague - I may have been guilty of exaggeration for the sake of illustration - it's a habit I've been trying to get rid of for about a hundred years.

No problem. I think we are on the same page about it.

Try JPR if you buy a lot of passives or "stock" semiconductors - you can save yourself a lot of money. http://www.jprelec.co.uk/ Their minimum order value is £30 excl VAT.

Not come across JPR, but I'll keep them in mind. These days my bits-boxes are pretty well stocked, so it tends to be only the odd special item I need, which is why I use the cheaper ebay shops a lot.
Incidentally, with Rapid there is no minimum order, you just have to pay p&p if it's below the 'minimum'.