Near eye spotter with built in illumination.

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Snapper
Posts: 425
Joined: 14 Feb 2014, 23:23
Location: East Sussex

Near eye spotter with built in illumination.

Post by Snapper » 18 Jan 2015, 00:59

Parts finally arrived so i managed to get my spotter finished tonight. My plan was to build an all in one spotter that was small enough to hang round my neck or go in my pocket as I'm currently spotting with my scopeless rig, which is hard work and not ideal. It uses 2 18650 ex-laptop batteries (to which I added a protection circuit) to power a Exview mini bullet cam, CRT viewfinder and T20 - haven't tested the run time but I'm hoping for at least an hour.

This is it with a cheap 5-60 mm lens - it is small but won't let me see much without illumination.

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And this is it with a really nice Fujinon 50mm f1.4 that I got from Torchwood. I spent ages filing and adjusting so I could get this lens to fit as it is amazing in low light (no moon tonight and only starlight but I can make out my fence 40 yards away). I managed to get it on with 0.5 mm gap between lens and T20 but it is rather heavy so I will take it out a few times and see how I get on.

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There is no spare room inside so I couldn't quite fit an av out socket but I have one on my scopeless unit so not that important. There are 2 buttons, one for power and the other for the T20 and I drilled a couple of holes in the side to access the vewfinder brightness and focus adjusters.

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Things never go quite to plan but I am a bit peeved that the T20 appears to cause interference with the viewfinder when it is on low power, it is better with medium power but totally gone on full power. I will have to live with full power which is a shame as I wanted to use lesss illumination to save battery and remain more covert. Appart from the interference it is brilliant and well worth the effort, although a spotter with a separate torch could easily be made to fit a 40 x40x100 mm project box..........

Total build cost was just over £90.

andybig
Posts: 916
Joined: 11 Sep 2013, 00:24
Location: coventry

Re: Near eye spotter with built in illumination.

Post by andybig » 18 Jan 2015, 10:16

Nice build mate, :clap:

Radagast
junior librarian
Posts: 2617
Joined: 04 Apr 2013, 10:51
Location: Sydney Australia

Re: Near eye spotter with built in illumination.

Post by Radagast » 18 Jan 2015, 10:42

Sounds like the T20 uses PWM and this is causing the interference. From the flashlight wiki:
PWM
Pulse Width Modulation. A technique of varying the brightness of a LED by flashing it on and off very quickly, making it appear to the eye that the LED is dimmer. Good PWM is at such a high rate that you can't notice it. But if you wave your hand in front of the light and get a strobe effect, the PWM is getting too low. Some use current regulation which makes the light dimmer without PWM and is also more efficient.
I'm not into electronics so take this with a grain of salt. Perhaps a pot could be used to modify the current to a single mode driver to avoid PWM?

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Torchwood
Posts: 1601
Joined: 04 Oct 2012, 23:25
Location: Barnet, london

Re: Near eye spotter with built in illumination.

Post by Torchwood » 18 Jan 2015, 10:44

Brilliant :thumbup: looks great :clap:
I'm a fan ;)

Toni
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22-250jock
Posts: 2354
Joined: 07 Dec 2012, 17:53
Location: Burgess Hill, west sussex

Re: Near eye spotter with built in illumination.

Post by 22-250jock » 18 Jan 2015, 11:14

cracking job there Snapper :clap: :clap:

nice and compact :thumbup:

cheers jock
“When guns are outlawed, only the Government will have guns. The Government - and a few outlaws. If that happens, you can count me among the outlaws.”
― Edward Abbey,

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some bloke
TRADER MEMBER
Posts: 7544
Joined: 27 Jan 2012, 16:14
Location: Cornwall or Leicester

Re: Near eye spotter with built in illumination.

Post by some bloke » 18 Jan 2015, 11:18

I like the look of that and if I were an 'on foot' shooter think I'd do something like it. It's amazining how much difference there is between the zoom CCTV lenses and fixed mag lenses.
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nealh
Posts: 290
Joined: 15 Oct 2013, 23:50
Location: Monroe, Louisiana

Re: Near eye spotter with built in illumination.

Post by nealh » 18 Jan 2015, 15:09

:thumbup: Nice build. Can we get a photo of the inside> :clap:
I love this country; it's the damn government I'm afraid of!

Snapper
Posts: 425
Joined: 14 Feb 2014, 23:23
Location: East Sussex

Re: Near eye spotter with built in illumination.

Post by Snapper » 18 Jan 2015, 15:33

nealh wrote::thumbup: Nice build. Can we get a photo of the inside> :clap:
I will do that later, but in the mean time here is a shot of most of the components that fit inside.

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Snapper
Posts: 425
Joined: 14 Feb 2014, 23:23
Location: East Sussex

Re: Near eye spotter with built in illumination.

Post by Snapper » 18 Jan 2015, 15:36

Radagast wrote:Sounds like the T20 uses PWM and this is causing the interference. From the flashlight wiki:
PWM
Pulse Width Modulation. A technique of varying the brightness of a LED by flashing it on and off very quickly, making it appear to the eye that the LED is dimmer. Good PWM is at such a high rate that you can't notice it. But if you wave your hand in front of the light and get a strobe effect, the PWM is getting too low. Some use current regulation which makes the light dimmer without PWM and is also more efficient.
I'm not into electronics so take this with a grain of salt. Perhaps a pot could be used to modify the current to a single mode driver to avoid PWM?
Its more interference rather than flickering as there are lines that appear on the CRT.

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blueeyes
Posts: 745
Joined: 22 Oct 2012, 11:39
Location: Bonny Scotland

Re: Near eye spotter with built in illumination.

Post by blueeyes » 18 Jan 2015, 15:58

Like that nice and neat and compact :thumbup:

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