Project by Clewsy; Rad10

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1

Clewsy just shared a new project: "Rad10"

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I wanted a self-contained internet radio with the following criteria:

Reasonably compact/portable.
Only required an external connection for power (i.e. wireless internet access).
Simple controls for volume and mute-toggle.


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Hi Clewsy,

I’m looking to make something pretty much identical to this and have a few quick questions as my hardware knowledge is a bit lacking!

You went with a stereo amplifier but a single speaker? Would this cause issues or is there a way to change the signal to mono before outputting?

What spec Power Supply did you need to run this?

Any chance of more info on the wiring setup as I’m looking at using exactly the same parts etc.

Cheers mate

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Hi Nathan, I’ll see if I can help;

For my purposes, the audio hardware is doing the trick. A couple of notes;

  • I’m using only one of the amplifier outputs, I did no hardware bridging. The mixing to mono was done in software. Regrettably I can’t seem to find the guide that I ended up following and I can’t remember the details. I do recall that it wasn’t as easy as I expected and ended up requiring a fair amount of googling and playing with some settings. It can be done though.
  • Depending on your intended usage, you may want to consider volume; I almost exclusively use the unit for streaming Triple J when I’m working on projects or sitting at the computer. I generally have the volume set anywhere between about 75% and 90%. My point being, the hardware I went with may not be appropriate for use in noisy environments.

Regarding the power supply, I’m using a compact 5V 3A plug pack. I think I picked it up from Jaycar years ago. I believe the max current draw from the amplifier should be around 840mA (based on 2.8W amp w/ 4ohm speaker). I’m using wifi on the RasPi3 which increases its current draw but I reckon (with no evidence to support) I could get away with a 2-2.5A supply.

Regarding the wiring info, I guess there’s a few parts to it:

  • The audio wiring consists of a 3.5mm jack (for RasPi audio output connector) to which I wired up only the ring and sleeve for the right channel. The other end went to the amplifier input R+/-. So 3.5mm jack ring to amp R+ and 3.5mm jack sleeve to amp R-. Then the amplifier screw terminals for the right channel went to the speaker.
  • The encoder wiring I noted in the code. Encoder channel A went to RasPi pin 15. Channel B went to RasPi pin 16 and the encoder toggle button went to RasPi pin 1. Note, these pin numbers are in accordance with the WiringPi library numbering pinout which is different to the RasPi GPIO numbers.
  • Then there’s the power wiring. Input from a 2.1mm jack has ground wired to everything (RasPi, amp and encoder). Similarly the 5V line is wired to everything but via a power toggle switch. For power to the RasPi, I connected to the GPIO and used the multiple ground and +5V pins there to distribute to the encoder and amplifier.

I hope some of this is useful but feel free to send more queries.

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Thanks for the reply. I’ll get back to you later with some more questions once I’ve had a closer read. My biggest lack of knowledge is around power requirements. As such I’ve got a 12V 5A DC which I was going to wire up to the amp and then across to the Pi. It may well be overkill power wise but would dangerous overkill?

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Hey Mate, you don’t want to use that supply unless you’ve got some way of dropping the voltage down to around 5V. Having lots of current available is fine (the gadgets will just draw as much as they need) but you’ll need to keep the voltage within the tolerance range of the devices. For the amplifier I used that’s 2.7-5.5VDC. You can find other amplifier modules with a wider and/or higher voltage range. However the Pi itself is a 5V device. I’m not sure what range it can tolerate, but I would imagine it would only be something like 4.5-5.5V as it’s designed to be powered from USB.

Unfortunately I think your 12V supply would probably do some damage if connected directly.

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Well, I’ve got all the parts with a 5V 2A power supply hooked up and seems to work well. Only this is the speaker is very quiet. Ive got the volume bumped right up and its just not putting out much sound at all. Could this just be to do with getting the software mixing from stereo to mono correct? Ive tried different gain settings on the amp which does seem to help a little.

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Hey Nathan, sorry for the late response - I’ve been on holiday. Have you had any luck with the volume issue?

Not sure what the problem might be off the top of my head, but maybe try connecting the speaker to the other channel and see if it’s louder? If so then that would confirm your suspicion of mixing being the cause.

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Hey @Nathan11486, perhaps also check that the output impedance of your amplifier matches the impedance of your speaker, impedance mismatches can cause weird issues.

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Hey good point Sam. Nathan you mentioned you were building something pretty much identical - if you used the same components I listed in the description then you’ll have a 4ohm speaker. The amp module outputs 2.8W to a 4ohm speaker but only 1.7W to an 8ohm speaker. If you’re using a higher impedance speaker, you may have lower volume.

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Got it sorted thanks. I ripped some Bose speakers apart and using those with the 20W amp instead. I think they’re 8 ohm. Sounds pretty decent, certainly loud enough now! Could do with some more Bass. Just about to start integrating the rotary encoder now, but pretty happy so far.

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Awesome, please keep us posted. I’m keen to see the final project.

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Excusing my horrible woodworking skills it’s worked out well. Pumps out some good sound. I need to add a Ground Isolator though as there is quite a bit of static which I believe is from sharing the same power source.

It’s running RuneAudio and connects over WiFi or Lan. When there is no network available it becomes a hotspot so you can still control with the phone.

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Mate that’s awesome, looks great!

Did you get the encoder working OK for volume control? Just wondering if you used the code I linked in the original project description.

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Sure did. Took a bit to get it running ok on RuneAudio but got there in the end thanks. Might even put a small lcd in next

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