We can't stop here. This is bat country!

[PRR]

Cheap stuff like my SammWhoo cellphone does not get coating. iPhone might?

Likewise you probably take good care with your stage-pedals and bat-talkers, or at least won't complain if 9 years in damp storage mucks it up. No coating.

Life-saving devices in harsh environments, like my kitchen or garage, the fire safety authorities might like some protection from humidity and rot.

[PRR]

I need a portable device to record the sound onto - ... (I don't own anything cool like a Zoom recorder)

I got one of these. It may have taken weeks but it did come. It looks better than you expect for under $25, but I have not been arsed to try it yet. There are several vendors. Some say "sale" but they are all the same price within a buck.
https://www.ebay.com/itm/263898436864
EZCAP Music Digitizer 3.5mm RCA Audio to MP3 Capture Recorder To SD Card USB

EZCAP Music Digitizer Convert old analog music to mp3 format and save to USB Flash Drive or SD Card,NO Need PC
Features:
Stand alone, no computer required.
Automatic partition.
With Playback, ca check the recorded music on device.
With remote control, can get all the functions by it.
Mini USB power.
With 3.5mm and 2 RCA audio input selections.
 
Specification:
Storage Media: USB drive, SD card
Audio Input: 3.5mm audio, 2 RCA L/R audio
Audio Output: 3.5mm audio
Converter Format: MP3
Bit Rate: 128Kbps
User Interface: Record button, IR remote control, LED for working status
Power supply: Mini USB port power supply (5V DC adapter)
Item size: 6.5 * 5.8 * 2.2cm / 2.56 * 2.28 * 0.87in(L * W * H)
Item weight: Approx. 51g / 1.8oz
Package size: 14.7 * 10.9 * 3.9cm / 5.79 * 4.29 * 1.54in(L * W * H)
Package weight: 151g / 5.37oz
old Amazon review (2 star) https://www.amazon.com/product-reviews/B06XN5F6NB?reviewerType=all_reviews
Company webpage: https://www.ezcap.com/ezcap241

[moid]

Thanks Chillums - that makes sense for putting in a smoke detector that might get affected by dust / moisture etc.

[amptramp]

Conformal coating performs another function as well: it stops the formation of tin whiskers in lead-free solder.  Leaded solder does not form tin whiskers because the lead prevents whisker formation.

[jorg777]

Conformal coating performs another function as well: it stops the formation of tin whiskers in lead-free solder.  Leaded solder does not form tin whiskers because the lead prevents whisker formation.

I was working on an avionics product and one customer was insisting on leaded solder.  It was an issue because most customers require ROHS (lead-free) these days.  I think we resolved it by reminding them we had to coat it anyway for that environment.

[moid]

I got one of these. It may have taken weeks but it did come. It looks better than you expect for under $25, but I have not been arsed to try it yet. There are several vendors. Some say "sale" but they are all the same price within a buck.
https://www.ebay.com/itm/263898436864
EZCAP Music Digitizer 3.5mm RCA Audio to MP3 Capture Recorder To SD Card USB

EZCAP Music Digitizer Convert old analog music to mp3 format and save to USB Flash Drive or SD Card,NO Need PC
Features:
Stand alone, no computer required.
Automatic partition.
With Playback, ca check the recorded music on device.
With remote control, can get all the functions by it.
Mini USB power.
With 3.5mm and 2 RCA audio input selections.
 
Specification:
Storage Media: USB drive, SD card
Audio Input: 3.5mm audio, 2 RCA L/R audio
Audio Output: 3.5mm audio
Converter Format: MP3
Bit Rate: 128Kbps
User Interface: Record button, IR remote control, LED for working status
Power supply: Mini USB port power supply (5V DC adapter)
Item size: 6.5 * 5.8 * 2.2cm / 2.56 * 2.28 * 0.87in(L * W * H)
Item weight: Approx. 51g / 1.8oz
Package size: 14.7 * 10.9 * 3.9cm / 5.79 * 4.29 * 1.54in(L * W * H)
Package weight: 151g / 5.37oz
old Amazon review (2 star) https://www.amazon.com/product-reviews/B06XN5F6NB?reviewerType=all_reviews
Company webpage: https://www.ezcap.com/ezcap241

Thanks PRR, that's very kind of you - but I really would like something that records to WAV for higher quality audio (so I can edit it later). I have used a Zoom before (borrowed one from work once) so I know I really want one... it's the usual issue of there's always something more important (but less interesting and always more expensive that has to be bought first ) That device sounds impressive for such a small amount of money though! On the good news front I was able to listen to bats from about 20m (60feet) away with the improved bat detector - I could hear bats that I couldn't see... whereas before they had to be within about 4m (12 feet) of me for the detector to make any audio loud enough to hear.

[PRR]

I'm old enuff to remember when 128k MP3 was pretty good. And I have edited from MP3 source (yes, it musta re-coded byte-wise internally). And I have worked with artists less talented (maybe just less sober) than your bats.

I have no use for it and got it anyway just because I wanted such a thing for decades. Yes it needs level controls and meters and more choices of bitrate... I've seen such and it costs more than the 10 pound fire extinguisher or less-holey pants I really need.