UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Components and Circuits

Notices

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.

Reply
 
Thread Tools
Old 10th Oct 2019, 10:24 pm   #1
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,457
Default 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.
60 oldjohn is offline   Reply With Quote
Old 11th Oct 2019, 11:28 am   #2
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 13,547
Default 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.
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline   Reply With Quote
Old 11th Oct 2019, 12:15 pm   #3
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,457
Default 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.
60 oldjohn is offline   Reply With Quote
Old 11th Oct 2019, 4:48 pm   #4
Trigon.
Tetrode
 
Trigon.'s Avatar
 
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 99
Default 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) :

Click image for larger version

Name:	S004.png
Views:	31
Size:	22.2 KB
ID:	191708

Cheers
Trigon. is offline   Reply With Quote
Old 11th Oct 2019, 8:17 pm   #5
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 13,547
Default 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.
Attached Files
File Type: pdf cd4060b.pdf (1.54 MB, 4 views)
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline   Reply With Quote
Old 11th Oct 2019, 9:19 pm   #6
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,457
Default Re: Runback Time (SMD) Two hour off delay

Quote:
Originally Posted by Trigon. View Post
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) :

Attachment 191708

Cheers

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.
60 oldjohn is offline   Reply With Quote
Old 12th Oct 2019, 10:31 am   #7
Trigon.
Tetrode
 
Trigon.'s Avatar
 
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 99
Default Re: Runback Time (SMD) Two hour off delay

Quote:
Originally Posted by 60 oldjohn View Post
I wonder if there is a similar chip that did not need the output inverting.
The output polarity on the 6995 can be selected via the DIV input, but then the oscillator has to be stopped by a different method, possibly by feeding the output back to the reset.

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
Trigon. is offline   Reply With Quote
Old 12th Oct 2019, 11:37 am   #8
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,457
Default 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.
60 oldjohn is offline   Reply With Quote
Old 12th Oct 2019, 12:22 pm   #9
Trigon.
Tetrode
 
Trigon.'s Avatar
 
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 99
Default Re: Runback Time (SMD) Two hour off delay

So something like this ?:-

Click image for larger version

Name:	cct001.png
Views:	29
Size:	25.0 KB
ID:	191744

Cheers
Trigon. is offline   Reply With Quote
Old 12th Oct 2019, 5:10 pm   #10
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,457
Default Re: Runback Time (SMD) Two hour off delay

Quote:
Originally Posted by Trigon. View Post
So something like this ?:-

Attachment 191744

Cheers

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.
60 oldjohn is offline   Reply With Quote
Old 12th Oct 2019, 8:53 pm   #11
Trigon.
Tetrode
 
Trigon.'s Avatar
 
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 99
Default Re: Runback Time (SMD) Two hour off delay

Quote:
Originally Posted by 60 oldjohn View Post
Is one a N channel Mosfet ? and the other a P channel MosFet ?
Indeed yes, nothing special. Just a first stab.

Quote:
Originally Posted by 60 oldjohn View Post
Anyone know where I can buy the LTC 6995-1 ?
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.
Trigon. is offline   Reply With Quote
Old 12th Oct 2019, 9:15 pm   #12
Vintage_RC
Tetrode
 
Join Date: Sep 2018
Location: Twickenham, London, UK.
Posts: 91
Default 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.
__________________
Alan G6PUB, BVWS
Vintage_RC is online now   Reply With Quote
Old 12th Oct 2019, 9:37 pm   #13
Trigon.
Tetrode
 
Trigon.'s Avatar
 
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 99
Default Re: Runback Time (SMD) Two hour off delay

Quote:
Originally Posted by Vintage_RC View Post
I would do it with an 8 pin PIC, probably need a delay loop within a delay loop because of the long period.
If it were me I'd use a 6 pin PIC. What do you need those all those extra pins for?

Cheers
Trigon. is offline   Reply With Quote
Old 12th Oct 2019, 9:41 pm   #14
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,457
Default 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.
60 oldjohn is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 12:29 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.