Ideal all-in-one case

[tj80]

Just wanted to share a very handy case for those who want to fully enclose the PAW including the USB devices:

http://www.maplin.co.uk/p/hammond-handheld-project-case-series-light-grey-165x100x32mm-n21gc

I have used one of these and packed the following inside:
- Raspberry Pi 2 and PAW bridge
- GPS dongle (removed from case)
- TV tuner (removed from case)
- Wifi adapter
- Short USB extension lead connected to a USB-powered Bluetooth audio receiver (removed from case)
- 2 x short antenna extension cables to move the connectors to the outside of the case
- Two volume controls connected to a simple passive audio mixer (2 x 10k resistors and 2 x 10k logarithmic pots)
- 3.5mm audio output jack
- Screw-locking DC jack for power - supplied in my case by an external USB battery pack

My iPad connects to the Bluetooth audio receiver to get Skydemon's audio alerts, which are mixed with the PAW audio alerts and sent to the external jack.  I intend to pipe this into the intercom somehow.

It's a tight squeeze but it's nice and robust, and even after running for several hours the temperatures are fine.

Hope that helps someone!
Tim

[Richard]

Any chance of any pictures of your project inside and out and the items you used for audio Bluetooth etc

[AerialRob]

Details of the aerial connectors and power jack would be appreciated.
Your idea makes for easier transportation and a neater install which is something I have been trying to achieve.
Thanks

[tj80]

I'll try to get some photos but the forum is complaining they're too big so will have to resize them.

The Bluetooth receiver is from ebay (all of £2.88 delivered) - it only uses USB for power, no data connection, and has no battery. This is deliberate, as the battery ones enter power saving mode and by the time they have woken up have clipped the alert you were trying to hear!  It provides line output audio to a 3.5mm jack inside the case.

The antenna connections are extended to the case side panel with 15cm cables, again from ebay. Right angle SMA to panel mount SMA for the bridge, right angle MCX to SMA panel for the TV tuner.  I have replaced the TV tuner aerial with a stubby SMA GSM antenna.

For power I used a locking barrel connector (from, you guessed it, ebay). This has a ring which you tighten with your fingers to stop the connector coming apart.  I used a normal micro USB cable, cutting it into two.  About 2" at the micro USB end to plug into the PAW inside the case, the other end soldered to the panel mount jack. The other cut end of the cable has the mating barrel connector soldered to it and the USB connector goes to a USB power bank.

Cheers,
Tim

[Richard]

Hi if your photos are too big you can take them with your iPad and email them to your self and send them in a smaller size you will then be able to put them on the forum.

Links to the eBay items would also be useful

Thank you

[tj80]

This forum is driving me mad between tiny file size allowances, filename extension rules and the need to wait between multiple posts!     Have to split into two posts because the total attachment limit is only 512kb per post - anyway, here's the outside.

[tj80]

Here's the inside - slightly embarrassing, it's not pretty!  The PAW is in at a slight angle because clearance is so tight I needed the extra space for the USB extension running to the Bluetooth receiver!

Parts (some are now out of stock but just search for another seller):

PAW antenna pigtail:
http://www.ebay.co.uk/itm/291504348413

TV tuner antenna pigtail:
http://www.ebay.co.uk/itm/262116776458

Stubby ADSB antenna:
http://www.ebay.co.uk/itm/222099443052

Locking DC barrel connector:
http://www.ebay.co.uk/itm/381407620023

USB extension cable:
http://www.ebay.co.uk/itm/400708565329

Bluetooth audio receiver:
http://www.ebay.co.uk/itm/331855014510

Volume control pots:
http://www.ebay.co.uk/itm/262314517795

2 x 10k resistors (from the parts box - get from ebay, Maplin, etc)

Cheers,
Tim

[Richard]

Tim,
    Thank you for the pics. Your efforts have are very helpful Thank you.

Did you join the audio output from the Rasburry and the Bluetooth together to crate one output for connecting with the aircraft or headset audio?

Your power input is still USB but you have used jack conections instead of the standard Nino USB? What leads did you use or did you make your own?

Your power light is also USB 5v ?

I like it!!!

[tj80]

Hi Richard,

Yes, a passive mixer circuit combines the Bluetooth audio (ipad) and PAW audio and this is sent to a single 3.5mm jack. This works well as a line output tested with a small powered speaker - but I do not have an auxilary input on either the aircraft or headset so am thinking of piping it into a rear mic socket to feed into the intercom.  I have lashed together a cable using an old headset mic jack and a capacitor to block the DC bias from the intercom, but haven't yet had a chance to test it in the aircraft and I fear the audio level may be too low.

For power I simply cut a normal micro USB lead into two. About 2" of cable left at the micro USB plug end, this is connected to the Raspberry pi inside the case and the cut end is soldered to the panel mounted DC barrel connector fitted to the side of the case. The other end of the cut USB cable is used to plug into the external UsB power bank, with the cut end soldered to the mating DC barrel jack. I used the DC barrel jack for two reasons - first, I could not find a panel mounted micro USB connector. Second, the screw locking mechanism is much more solid than a Micro USB connector and is hopefully less likely to come apart or get damaged.

The power light is just an LED from the parts bin in series with a 220ohm resistor attached to the DC barrel connector. I also bought some plastic fibre optic cable from ebay and may try using this as a light pipe to extend the GPS receiver LED to the front panel.

All the gubbins are held in place with judicious use of hot glue!

Cheers,
Tim

[Ian Melville]

but I do not have an auxiliary input on either the aircraft or headset so am thinking of piping it into a rear mic socket to feed into the intercom

This works well enough, but make sure you use a mic socket that will not pass the alerts into the radio if you have the PTT pressed. Some of the better audio panels prevent this from happening from the rear sockets, but he cheap ones do not. My audio system is so crude that even the P2 chatting will broadcast if I press the P1 PTT

[tj80]

Fortunately I know the rear headset sockets are "dead" as far as the PTT are concerned (and the P1/P2 PTT switches are correctly wired to transmit only from the relevant mic!).

I have only been able to test the setup so far using an adapter circuit I built to interface a headset mic to a PC's mic (essentially emulating an aircraft's mic socket).  Although it does work, the audio level is very low to the point of being unusable - I've just used a 10uF electrolytic in series plus a 10k pot as a potential divider.  Regardless of the pot's setting the volume is still way too low.  Any ideas?

Thanks,
Tim

[tj80]

Just as an update, I took the PAW flying again on Sunday and tried out the audio input into a spare rear mic socket.  It did work, but as feared the audio level was far too low.  I heard a very quiet "Traffic, danger" while waiting the hold as a Cessna landed right in front of me but above idle the alerts were drowned out completely.  I've ordered a tiny 5v audio amplifier from eBay and will give that a go.

Cheers,
Tim

[Ian Melville]

Tim, did you set the volume to max in the PAW configure? I have to do this every time I power up the unit, and find the volume just OK, and I am a bit Mutt  and Jeff. Looking forward to the next release when this will be fixed.

[tj80]

I did, yes - think if it was directly connected it would be OK but with the attenuation from the passive mixer it's not.    Might also have been drowned out by the constant noise from my wife and toddler in the back!

Cheers,
Tim

[exfirepro]

Hi Tim,

Nice job! You seem to know what you are doing so I'm sure you'll sort out the 'volume' issue. The pre-amp should do the trick. Presumably it has variable gain as you probably won't need much.

As you may have read elsewhere, Lee intends to sort the 'audio volume adjust' so it remains at the previous setting when the PAW is switched off, which will take that out of the equation. Hopefully that will be in the next update due for release shortly. I would be very wary of venturing down the route of back seat noise generator attenuation 😷 - might curtail your flying a bit !

Let us know how you get on.

Regards

Peter