Speaker for robot

[3v0]

I would like suggestions for a speaker to use with a small robot. It needs to do a decent job with voice and be no larger then two inches. Smaller would be better but clear sound is the first concern.

 

[Hank Fletcher]

My local dollar store still has a kind of docking bay (I think for a Gameboy?) for about $3. That includes two speakers (about 1" each, I think), whatever motor it's using for its rumble feature, 4 rechargeable AA batteries, and the adapter plug!

 

[Krumlink]

https://www.jameco.com/webapp/wcs/s...|a&h0=&h1=&showImages=0&action2=Show+Pictures

A bunch of small speakers.

 

[Nigel Goodwin]

A bunch of small speakers.

Now come on! - there MUST be a collective name for a quantity of speakers, perhaps people can make suggestions?.

 

[3v0]

Posting a catalog page does not help me determine which one to choose. Some small speakers like the ones used on some PCs for beeping are very bad. A 1 or 2 inch speaker is not going to sound great. I just want the best shot at sounding good as possible without ordering and testng N speakers.

EDIT Krumlink:
I would guess you spend more time then I do looking at sites that sell robotic parts. What are they selling for speakers intended for robotic voice ?

 

[jumides]

how about using cellphone speaker (polytone).

 

[Krumlink]

https://www.jameco.com/webapp/wcs/s...&catalogId=10001&productId=355514&pa=355514PS

I have a speaker similar to this one that I am using. It is cheap, small small power input (0.1W) and can operate from 500hz to 20khz.

 

[Hank Fletcher]

Now come on! - there MUST be a collective name for a quantity of speakers, perhaps people can make suggestions?.

A bunch of small speakers.

The Republican candidates?

Alternatively, if you're looking for a place that sells an assortment of speakers, I suppose you're looking for a polyphonopoly.

 

[kchriste]

Some questions:
How much power do you want it to handle?
What impedance do you need?
If you want it to be loud, then look for one with a higher SPL spec.
Are you planning on mounting it in a sealed enclosure or is it going to sit naked outside the robot for that "fem-bot" look?
You might be able to salvage one out of an old portable radio.

 

[3v0]

Some questions:
How much power do you want it to handle?
What impedance do you need?
If you want it to be loud, then look for one with a higher SPL spec.
Are you planning on mounting it in a sealed enclosure or is it going to sit naked outside the robot for that "fem-bot" look?
You might be able to salvage one out of an old portable radio.

Surplus and salvaged speakers are of unknown quality. I would rather use a new first run unit.

I have just started playing with IC AMPs and do not know how much power will be required to get a decent volume in a room of 20 or so people. In a group that size I would expect a few to be talking or whispering to each other at any given time. SPL: Speaker Pressure Loudness, did not know that. Thanks.

Regarding impedance as long as the speaker and AMP match I am not picky. I have not chosen either yet.

These robots have a 6x3x2 inch body that the gearbox bolts to. The first attached image shows the box. The box has slots that I am using for holding various PCBs.

The best spot to mount the speaker would be on a 2x3 wall.

Up to now I had not considered an enclosure. I do not know if one is possible given the size. The box comes with a lid that could be shortened to cover the speaker section of the body with a partition in the 1st or 2nd slot from the end wall. Maybe stuff it with polyfill to absorb the energy from the back side of the speaker.

The second attached image is of the current test setup. The processor board has a PIC18F1330 with a single I2C socket. I just finished the board on near side of the breadboard. I have yet to power it up. It has a MAX7480 butterworth filter on the top and a MAX9716 amp IC on the bottom. The next iteration may have a Microchip I2C digital pot to set the amp volume.

 

[jumides]

The best spot to mount the speaker would be on a 2x3 wall.

sony speaker(oval type) from tv are good sound quality. size approx. 2" x 3".

 

[kchriste]

Regarding impedance as long as the speaker and AMP match I am not picky.

Generally speaking, you'll be able to get more power out of a 4hm: speaker/amp than a 8 hm: speaker/amp for a given supply voltage. You shouldn't need more than 2-4 watts to be plenty loud enough in an average sized room. Even 0.5-1W should be fine. Probably more important is to choose an amp that has a low power shutdown mode to save power because the robot probably won't spend much time speaking.

Up to now I had not considered an enclosure.

It is a good idea because the sound off the back of the cone is out of phase with the sound off the front and they tend to cancel at lower frequencies. The only issue you'll probably encounter with an enclosure is if it isn't stiff enough and it may resonate at certain frequencies. Dampening the enclosure with sound Pollyfill is a good idea as long at it doesn't cause the rest of the circuit to overheat.
I see you already have an amp and speaker setup. It should work well at 1.4W output.

 

[the dude of dudes]

I plundered an old PC external speaker for my bot. It's 4ohm, 3watt and measures about 1.5"x3", best of all it was free. I tried smaller speakers from old toys, but couldnt hear my bot speaking over the sound of the tomiyama gearbox. Only problem is it sucks a lot of power, driven by a LM386. I'm currently looking for a bigger power source because of this.

 

[blueroomelectronics]

I was going to have a kit with a simple 2" speaker mounted in a small Lab-easy case. If you find a design that works with as little as 5V I'd be happy to make it into a PCB.
**broken link removed**

 

[3v0]

Generally speaking, you'll be able to get more power out of a 4hm: speaker/amp than a 8 hm: speaker/amp for a given supply voltage.

That makes sense.

You shouldn't need more than 2-4 watts to be plenty loud enough in an average sized room. Even 0.5-1W should be fine. Probably more important is to choose an amp that has a low power shutdown mode to save power because the robot probably won't spend much time speaking.

The amp I am playing with has a 10nA Low-Power Shutdown Mode.

It is a good idea because the sound off the back of the cone is out of phase with the sound off the front and they tend to cancel at lower frequencies. The only issue you'll probably encounter with an enclosure is if it isn't stiff enough and it may resonate at certain frequencies. Dampening the enclosure with sound Pollyfill is a good idea as long at it doesn't cause the rest of the circuit to overheat.
I see you already have an amp and speaker setup..

There is a lot of info on the web about enclosure design. I do not think much will apply but I will look at it just the same.

The speaker in the image is the best small speaker I had on hand. It is too big for use on small robots and I do not have a source for it. I am looking for a good speaker in current production so the source will not dry up for a while. Also better chance of having tech info on it.

Thanks a bunch.

 

[3v0]

I was going to have a kit with a simple 2" speaker mounted in a small Lab-easy case. If you find a design that works with as little as 5V I'd be happy to make it into a PCB.

The MAX9716 does that but does not come in DIP. The samples I am using are in the uMAX package. Could be that the newer designs are all going to be SMD of some sort.

♦ 2.7V to 5.5V Single-Supply Operation
♦ 1.4W into 4Ω at 1% THD+N
♦ 10nA Low-Power Shutdown Mode
♦ 73dB PSRR at 1kHz
♦ No Audible Clicks or Pops at Power-Up/Down
♦ Internal Fixed Gain to Reduce Component Count
(MAX9717B/C/D)
♦ Adjustable Gain Option (MAX9716/MAX9717A)
♦ BTL/SE Input Senses when Headphones are
Connected (MAX9717)
♦ Pin Compatible with LM4890 (MAX9716)
♦ Pin Compatible with TPA711 (MAX9717A)
♦ Available in Compact, Thermally Enhanced μMAX
and TDFN (3mm x 3mm) Packages

I intend to spend some time looking at this sort of little amp. If I find one in a DIP package that works on 5V I will let you know.

 

[blueroomelectronics]

Hmm how small is uMAX (smaller than SOIC?) with 8 pins might be a possibility... The MAX9716 looks good.

 

[3v0]

They are package is 3x5 mm including pins. Pitch is .65 BSC mm or .0256 inches.

Thinking BSC is between center of pins or similar ?

Datasheet uMax package diagram is near the bottom.

 

[Hero999]

Surplus and salvaged speakers are of unknown quality.

Don't let that put you off.

My advice is to go to your local dump and pick up an old radio with 2.25" speakers in. The chances are that they'll be 8hm: 0.5W and will sound reasonable. Also make sure that have a paper cone (small mylar speakers sound crap), generally if they have a silver dome and black cone you can be reasonable sure that they'll be reasonable quality.

 

[3v0]

I am putting this together as a project that teachers and students can build. Most teachers are not willing to visit a dump and scrounge for old speakers that may or may not work. In general I love to scrounge but speakers that sort of work could drive the builder bonkers.

At some point the students robots will be demonstrated for the school board. It would be better if they had clear voices.

I have 2 candidates so far that I can buy from Mouser. They are 4 Ohm speakers of the right size, can handle the 1.5 watt amp, and have SPL's over 80. They were about $2 and $7.50.

**broken link removed** and **broken link removed**