Author Topic: Cave communication for a rescue team  (Read 1715 times)

Offline aricooperdavis

  • obsessive maniac
  • ***
  • Posts: 406
  • Exeter | The Lakes
    • Cooper-Davis.net
Re: Cave communication for a rescue team
« Reply #25 on: November 07, 2019, 10:03:22 pm »
The field telephones we used at ResCon didn't belong to Mendip, they were brought down by BCRC comms officer from the North Wales team.

My mistake, thanks Estelle! Very good of the North Wales team to bring them down, they were good bits of kit to have a play with :)

Offline Stuart France

  • addict
  • **
  • Posts: 147
Re: Cave communication for a rescue team
« Reply #26 on: November 08, 2019, 05:16:29 pm »
Single-wire phones are your cheapest and easiest way forward.  I build a batch of about 30 handsets and 10 base stations for UK rescue teams that ordered them during 2013.  They paid £43 per handset and £64 per base station which represents the parts rather than labour.

These were designed to eliminate all known hassles with the previous generation of caving field phones:
1) stop people from turning them off in the cave (complicated procedure to turn it off once it is on)
2) make them last on three AA cells for over a day's use and step up to a constant 12 volts internally regardless of battery voltage droop
3) turns itself off after many hours of inactivity
4) can send call tones and roger beeps
5) military standard waterproof mic/speaker
6) circuit is potted (not the battery of course) and a single IP68 push button to control everything.

It's written up in the BCA CREJ No.82
http://bcra.org.uk/pub/cregj/index.html?j=82

but you need a login to download the PDF of the article.  That article in Word format and other info about it is in zip file links at:
http://www.linetop.co.uk/cssdata/swt.htm

As to which teams might have spare units they might give away to a good cause:  Gloucester GRG took 10 handsets and SMWCRT took 8.

I may have a few spare PCBs and excess components somewhere, but I've not looked at this since 2013!

Offline Jopo

  • obsessive maniac
  • ***
  • Posts: 394
Re: Cave communication for a rescue team
« Reply #27 on: November 09, 2019, 01:20:37 am »
Thought you produced more than that Stuart. Deserved to, fking good sets.
Jopo

Offline yuvals

  • regular
  • *
  • Posts: 30
Re: Cave communication for a rescue team
« Reply #28 on: November 10, 2019, 09:29:31 am »
Single-wire phones are your cheapest and easiest way forward.  I build a batch of about 30 handsets and 10 base stations for UK rescue teams that ordered them during 2013.  They paid £43 per handset and £64 per base station which represents the parts rather than labour.

These were designed to eliminate all known hassles with the previous generation of caving field phones:
1) stop people from turning them off in the cave (complicated procedure to turn it off once it is on)
2) make them last on three AA cells for over a day's use and step up to a constant 12 volts internally regardless of battery voltage droop
3) turns itself off after many hours of inactivity
4) can send call tones and roger beeps
5) military standard waterproof mic/speaker
6) circuit is potted (not the battery of course) and a single IP68 push button to control everything.

It's written up in the BCA CREJ No.82
http://bcra.org.uk/pub/cregj/index.html?j=82

but you need a login to download the PDF of the article.  That article in Word format and other info about it is in zip file links at:
http://www.linetop.co.uk/cssdata/swt.htm

As to which teams might have spare units they might give away to a good cause:  Gloucester GRG took 10 handsets and SMWCRT took 8.

I may have a few spare PCBs and excess components somewhere, but I've not looked at this since 2013!

Thanks, that is relay helpful.
Why do you need base station? As far as I understand "Michies" are symmetrical and can be used for both ends of the system.

Offline Fred

  • addict
  • **
  • Posts: 112
Re: Cave communication for a rescue team
« Reply #29 on: November 10, 2019, 11:29:38 pm »
I'm sure Stuart will reply but having a little knowledge of the Gloucestershire Cave Rescue Group's units I can say there aren't any spare - they are still very much part of their frontline kit.

Regarding the handsets, your right you don't need a specific base station unit. In fact there is a "base station mode" into whcih any unit can be switched - this turns off the auto shut down for example.

The specific base station units have an external speaker and an input for external 12v power - no issue of batteries running out and more appropriate for the control location. The increased price reflects the extra components.
The one thing to remember about an adventure is that if it turns out the way you expect it to, it has not been an adventure at all.