Nestbox camera power supply.

eclectic

Moderator
I've just bought a 2.4G Nestbox camera.
On the bench, all seems to work OK.

The receiver is mains powered, so no problems next to my computer.

The transmitter needs 8 volts, but,
I cannot run a permanent mains lead to the proposed nestbox site.
(about 10 metres, L.O.S).
And, I do not want a transmitter continuously "sending".

Therefore, I was thinking of the following:

1. 7 AA NiMH 2000mAh in a sealed and sheltered box,
rather than a weedy PP3 (~170mAh).

2. A PICAXE circuit to switch the power on/off as required.

3. A 433MHz transmitter to switch on the PiCAXE output,
to a 5v latching relay.

When off, the PICAXE "sleeps".

I'm not too worried about the battery drain, as I can change them every few days.
Any comments or better suggestions?

e
 

fernando_g

Senior Member
It is a good idea to use latching relays, as normal relays are typically power hogs. Check the NAIS relays, they have a large selection.

How tightly regulated should the 8V supply be? Tell us the Min/max values to determine whether you require 8AA cells instead, followed by a LDO regulator. I don't think there are 7 cell AA holders, but 8 cell or even a pair of 4 cells are very common.
 

goom

Senior Member
8 cell NiMH battery packs, particularly in sub-C size, are readily available since they are commonly used for radio control hobbies. They typically have capacities ranging from 2000 to 5000 mAh.
 

eclectic

Moderator

AllyCat

Senior Member
Hi,

Yes, certainly don't use a PP3. Seven rechargeable AAs will give about 8.5 volts, but don't foget they may be around 10v immediately after charging. You could use one 4 cell and one 3 cell holder, or 2 x 4 cells with a "placeholder" (dummy, short-circuit) cell in one bay. In practice, 6 cells might be sufficent, or a pair of Lithium rechargeables (2 x 3.7 volts) might be preferable. But "shipping regulations" (Royal Mail or air post) can be a pain with Lithiums now.

3. A 433MHz transmitter to switch on the PiCAXE output,
to a 5v latching relay.
When off, the PICAXE "sleeps".
Do you mean a receiver (near the nestbox) which the PICaxe will monitor to decide when to turn on (the camera power)? The receiver will be the major battery drain (but probably quite acceptable at a few mA). Even an "awake" PICaxe only needs around 0.5 mA, but it probably will need to be actively monitoring the receiver output. Cheap (superregenerative) receivers generate continual "hash" that needs to be decoded to look for a valid character sequence, but even higher quality (superhet) receivers might receive repeated "foreign" signals from weather stations, etc., etc. on the now heavily-used 434 MHz band (so wakeup from interrupt might not be the best strategy).

Cheers, Alan.
 

eclectic

Moderator
snipped

Do you mean a receiver (near the nestbox) which the PICaxe will monitor to decide when to turn on (the camera power)? The receiver will be be the major battery drain (but probably quite acceptable at a few mA). Even an "awake" PICaxe only needs around 0.5 mA, but it probably will need to be actively monitoring the receiver output. Cheap (superregenerative) receivers generate continual "hash" that needs to decoded to look for a valid character sequence, but even higher quality (superhet) receivers might receive repeated "foreign" signals from weather stations, etc., etc. on the now heavily-used 434 MHz band.

Cheers, Alan.

I must not post when I have a stinking cold!

The 433 Transmitter on my desk > 433 Receiver near the battery >
controls the 2.4G camera transmitter.

If it doesn't work first time, or I break something,
it's still a cheap (ish) educational exercise.

e
 

ZOR

Senior Member
OK thanks eclectic, was just a thought, hoped to pay you back for all help you have always given me. Regards
 

ZOR

Senior Member
Hi eclectic, all my cameras go into a dedicated 8 camera DVR. I had a friend who had something in his loft, but I could not find suitable dongles or devices in the UK that were sensibly priced, and in the end went to Ebay and got an SD card recorder which was programable to record schedules, constant, or on movement. If I come across anything I will post it.

http://www.ebay.co.uk/sch/sis.html?_kw=Newest+NTSC+Mini+SD+Card+Motion+Detection+Digital+automatic+video+Recorde+Black&_id=231053659272

These might not be any good as they would need more power at the location.
 
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