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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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10th Oct 2019, 10:24 pm | #1 |
Dekatron
Join Date: Dec 2004
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Runback Time (SMD) Two hour off delay
Is there a device that will switch 3V 3Ma off after about 2 hours. Must be no larger than 12mm x 20mm x 4mm H.
TIA, John. |
11th Oct 2019, 11:28 am | #2 |
Dekatron
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Location: Leominster, Herefordshire, UK.
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Re: Runback Time (SMD) Two hour off delay
Probably.
If you can cope with SMDs, you could build one yourself using a 4060 or similar oscillator/divider chain CMOS chip and a few discrete bits. 50 thou blob board is readily available.
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11th Oct 2019, 12:15 pm | #3 |
Dekatron
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Re: Runback Time (SMD) Two hour off delay
I was aware of the 4060 and regularly use 0.7mm board to make the PCBs for SMD. My only concern is the 1000uf cap size wise. If I can use the 4060 without a large cap, the 4060 may work, just a shame there is not a ready made chip available.
John. |
11th Oct 2019, 4:48 pm | #4 |
Hexode
Join Date: Jun 2018
Location: Buckinghamshire, UK.
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Re: Runback Time (SMD) Two hour off delay
There are chips available but they cost a few pounds, e.g. the LTC6995, which is a 6 pin surface mount device which doesn't require a timing capacitor. (Useful to keep within your 4mm height limit !)
e.g. from the data sheet - a 1 hour auto shutoff timer (which would also need a fet or transistor to invert the output) : Cheers |
11th Oct 2019, 8:17 pm | #5 |
Dekatron
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Re: Runback Time (SMD) Two hour off delay
The 4060 is an oscillator-divider unit, so you can keep the capacitor size down since you can divide the frequency / multiply the period by up to 2exp14.
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11th Oct 2019, 9:19 pm | #6 | |
Dekatron
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Re: Runback Time (SMD) Two hour off delay
Quote:
Thank you Chris, but I think the LTC chip type is the chip to try, or I wonder if there is a similar chip that did not need the output inverting. The PCB may have to be 12mm X 12mm x 4mm H which would be possible using LTC6995. John. |
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12th Oct 2019, 10:31 am | #7 | |
Hexode
Join Date: Jun 2018
Location: Buckinghamshire, UK.
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Re: Runback Time (SMD) Two hour off delay
Quote:
Everything depends on how the timer is to be started and whether the timer itself is to be powered down at the end of the timeout. Cheers |
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12th Oct 2019, 11:37 am | #8 |
Dekatron
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Re: Runback Time (SMD) Two hour off delay
Circuit uses 3v 3ma powered from 3v lithium battery. I need to press the switch to turn circuit on, then after 2 hours switch off, no power at all to be consumed. The LTC chip sounds great if I can get it to work as stated above.
John. |
12th Oct 2019, 12:22 pm | #9 |
Hexode
Join Date: Jun 2018
Location: Buckinghamshire, UK.
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Re: Runback Time (SMD) Two hour off delay
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12th Oct 2019, 5:10 pm | #10 | |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
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Re: Runback Time (SMD) Two hour off delay
Quote:
Thank you for taking the time to draw the circuit, The two components with thee legs, Is one a N channel Mosfet ? and the other a P channel MosFet ? Anyone know where I can buy the LTC 6995-1 ? John. |
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12th Oct 2019, 8:53 pm | #11 | |
Hexode
Join Date: Jun 2018
Location: Buckinghamshire, UK.
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Re: Runback Time (SMD) Two hour off delay
Quote:
They do seem to be rare in the UK. Rapid appear to have 'discontinued' (?) the whole range. Mouser.uk and Digikey.uk list them at over £3 ea. but they're delivered from the US and the p&p would be £12 or so (for orders under £33). I eventually did find them in the UK at Anglia Live (an approved distributor). They're actually a bit cheaper, but again handling makes it £8.13 for one off, then £2.20 for each additional one. http://www.anglia-live.com/products/...N-lTC6995iS6-1 Cheers Last edited by Trigon.; 12th Oct 2019 at 8:58 pm. |
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12th Oct 2019, 9:15 pm | #12 |
Heptode
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Re: Runback Time (SMD) Two hour off delay
I would do it with an 8 pin PIC, probably need a delay loop within a delay loop because of the long period.
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Alan G6PUB, BVWS |
12th Oct 2019, 9:37 pm | #13 |
Hexode
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Re: Runback Time (SMD) Two hour off delay
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12th Oct 2019, 9:41 pm | #14 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
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Re: Runback Time (SMD) Two hour off delay
I will give Rapid Electronics a call on Monday in case they can help. The price quoted is a bit steep, for an item that could be £2.20.
Alan, a PIC may be the easiest but the programing is beyond me. I have a friend who might be able to help, another avenue to explore. John. |
4th Mar 2020, 8:42 pm | #15 |
Triode
Join Date: Dec 2015
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Re: Runback Time (SMD) Two hour off delay
Multifunction Delay Trigger Timing Chip Module Timing 2s - 1000h Timer IC F
eBay item: 292215199121 may do exactly what you want to do ! |
31st May 2021, 10:58 am | #16 |
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Re: Runback Time (SMD) Two hour off delay
Thread reopened at OP's request.
Cheers Mike T
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31st May 2021, 11:22 am | #17 |
Dekatron
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Re: Runback Time (SMD) Two hour off delay
Thanks Mike T, I have only just seen MikeM100 reply, I think it is this https://www.ebay.co.uk/itm/272581042....c101111.m2109 C005 Multifunction Delay Triger Timer. The board is 12mm x 12mm x 2mm. Available for around 40p each. The link shows pads P1 and P2 these are needed to set a time of more than a few minutes, make sure what you order has these. For ~ two hours I linked p2 and used a 390k resistor. You tube has this video about the C005. https://www.youtube.com/watch?v=C4C2H_3BU3o The timer can be set from 2 seconds to nearly 6 weeks!
John.
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