Audio (voice) - Stock 9X PCB

[JEANALTAYR]

if too old at first start the welcome message disappear jmi

would this sound module read a MMC card ? I have a 512Mb old one. but I could not test it yet cos' I don't have any output from my module...

[C.João]

it is an 100X MMC 512mb card. old but not ancient...

[C.João]

about the photos. will take them by the night. I'm off to help out on a bar/pub (sound issues. gonna re-wire the walls)

but I'll leave the layout I've used to create the veroboard. I took the 5V from the switch board (changed the VR there).

The attachment Sound module sch.png is no longer available

The attachment Sound module.png is no longer available

were they come. but the layout seems better... on this board I have some fly-wires for the telemetry signal conversion, signal and power to the amp. and a temporary 8ohm speaker.

top/parts

bottom/solders

[argo]

C.J - I know your frustration as I went through similiar before finding my SD Card was the culprit. I strongly recommend you go and buy a new SD Card - they are cheaper than your time and hammer!

Actually scrub the above, as you have problems with the serial lines out of the '574, with BL ok - correct? Here's an idea - you put your '574 in an IC socket, could you lift the output serial-line legs into free-air? Not nice bending IC legs but '574's are cheap! Then you could measure the output signals without fear that these are driving into a short -circuit. Also to check are 3.3V/5V constant - including underload (sorry obvious I know)? Unlikely to be the problem as you have the BL working.

If the BL is working, the rest of the '574 part of the circuit is very simple: input level -> to -> output level at every clock pulse (at a level 'low'). Other idea, when I was fault-finding mine I took the 9X out of the circuit and using a breadboard triggered my own pulses with input levels being set/reset by raising/lowering them with a 10k resistance to +3.3V/GND. With the clock held high via a 10k resistor, if you ground this at the Clk pin the '574 will clock the level it sees on the input to the output line. Actually a tip - on '574 powerup the outputs are default high, until the 1st clock pulse. With the 9X disconnected are you seeing '574 outputs as high at power on?

Sorry lots of ramblings! Hope you can find something that will help in there Best of luck - the end result is worth it.

[argo]

Guys just a SD Card observation:
I believe the voice modules are a little fussy with the SD Card, as I recently found I was getting a voice-message cut short consistently. On the PC that SD Card file was fine. The fix was to copy all the voice files onto the Card again (overwrite). Doing only this (no other actions) fixed that particular problem .

And just cause, here is a vid of my voice mod:
https://vimeo.com/48942588

The "you forgot me" alarm that we all love to hate:
https://vimeo.com/48942963



Edited as Vimeo Embedding does not seem to work with this forum

[jhsa]

[C.João]

I just got up. I'll try to breadboard my 74. yesterday I suspected one transistor since the pulses were very quick and did not look very square... but the backlight did work... I changed the clock transistor and now the backlight flickers on boot up. the only transistor that I don't suspect is the backlight one. today I'll swap the busy signal one.

as for SD-cards. I have more than one. and a MMC card as well. none of them seem to work... my module could have a problem...

[jhsa]

It must be possible to test the module..

[C.João]

I got the module working. it was a little mistake I made I removed the SD-card socket from the board in order to place it were its convenient. the problem is the Chinese manufacturers use the socket case as a jumper for GND so I had signals but no amp, etc. I lost time on this cos' I didn't look straight to it. its wonderful what a dumb job can do for you... I'm loosing all my skills :s

[C.João]

I'm off to solve the mystery of POPs on the output when using an amplifier.

the thing is simple: the amp-out is a PWM amp. so it will "pulse" from 0 to 3.3V quickly. with an bypass capacitor we can still ear a POP since the capacitor has to charge. this is not hard to solve. just bias the capacitor to be polarized at the 3V3 line and here you go! I'm testing a solution to do this simply.

plus: the speaker output is no good for an amp. even if I get rid of the pop's, it has a 'chirp' that I don't kile to hear.
by some mistake... the audio-L output is the same spk+ line so it wont cut it.

there is one pin that is the most appropriate to connect an amp and that it pin 10 on the sound module Chip itself! this pin has the 3v# offset problem (and goes high upon start of the sound: hence "pop")

I'll scope around and will try to find a solution.

since I don't really like the transformer solution...

[C.João]

possible solution found. its is simple enough for me. anyone care to test out and bake it better please report results

check the file attachment.

Pop-Kill (I prefer rock and Metal!)

pop-kill.png (5.02 KiB) Viewed 13601 times

[C.João]

note that this works good on the sound module chip pin 10. on a spk output I did not test (they have a chirp noise)

the pin 10 is freely available since it is one of the jumper the manufacturer made on the board.

feel free to test and report back

[C.João]

further testing made my decide on the amp I'll be using for the speaker. it is a small module I got over ebay some time ago based on a PAM8403 (stereo 3W THD:10% @5V) ultra sable and low noise. to bad it has 2 outputs that I won't be using one of them...

I don't really like the LM386 amp. I've used that before... noise. I hate noise...

[C.João]

possible solution found. its is simple enough for me. anyone care to test out and bake it better please report results

check the file attachment.

pop-kill.png

scratch that above! you always get the first "pop" and if you don't have any sound over a while (30sec to 1 minute), it will pop again. even so it is not a heavy pop. it wont hurt on headphones anyway.

[C.João]

Mike: I tried out one rotary encoder on the "other" lcd lines and it works! (switch included) it is glitchy but that could be my encoder and/or debouncing on the fw.

I could not "fix" entirely the "pop" issue. on idle the pin 10 of the IC is at 0V. when a sound is starting it rises to about 1V and then plays the sound. right after the sound stops the line goes low do 0V again.

a simple bypass capacitor will always do a "pop" because it has to charge so: series resistor could help but not fix, biase one capacitor like I did on a previous schema does help but not fix.

I may have to use a voltage follower (amp-op or transistor) and bias it on the output in order to ditch the pop's.

I don't have the internal sound module chip blocks so I just can't bias directly the pin 10 (that would be very easy and simple

[C.João]

news!

I got rid of the pop's noise passively!

I now have a chirp before any sound (module accessing the memory card) that I will try to get rid of, but it may be my supply lines.
so if anyone care to test this out I'll be happy for any feedback.

check the attachment

pop-kill 2

pop-kill.png (5.54 KiB) Viewed 13533 times

please note that C2 and R1 could be left out it the amp has them just like in this schematic (if the resistor is before the capacitor it wont work!)

[C.João]

please don't forget, pin 10 is the pin10 from the module IC itself! not the 10th pin of the module.

this pin is available on one of the jumper on the sound module.

I've tried to use the spk out's and they are noisy and "enhance" the sound with pwm artifacts. they are no good for an external amp.

[C.João]

I was going to make a complete schematic and a "tutorial" like document for the use of an external amp with the voice module but, about 50 views and no comments... I don't really thing its needed to do that...

[Flaps 30]

C.João - I am reading with interest your way around the problem with pops. I seem to recall that something was mentioned regarding this design characteristic, way back at around page 7.

It does seem (I haven't finished building my voice unit yet) that the speaker outputs rise DC wise just before a file is played. I am assuming that both the SPKR outputs rise at the same time, which would mean that no pop will be heard if the module is driving a speaker. If that is the case, then you are stuck if you want to use a single ended input amplifier. I would think that an amplifier that has a differential input (like the LM386) being driven by the SPKR plus and minus would be the answer to this issue.

[tigar]

I tried on my headphone out to connect a powered mp3 amp. It worked without distortion as long as I kept the input volume low. Maybe this approach is easier to implement? I don't have any electronics knowledge that's why I am waiting for final results.

[C.João]

the problem is not the spk+ and spk- being differential, I tried to use a differential amp-op on testings but, since it is a 'reactive' (pwm) output, it has noises. maybe some wont ear them cos' any ear or speaker are different.

with those 2 capacitors and resistors I got rid of the pop's and pwm noises. plus, it sounds a little bit fuller and richer. for me its a win-win

[argo]

Good to hear you got your module working CJ, trouble-shooting guide fits - if the BL is working look to the module or card
Interesting work on the pop elimination. I know the journey can be more fun than the destination, but now I have field tested the non-amped module I can say more volume is not really needed! I can hear the voice prompts in strong wind and would probably need to have it no louder if flying with other pilots. Just thought I'd let you know

[C.João]

the thing is: I don't need the amp for loud volume. I need it for headphones... the pwm output is pretty much uncontrollable for that... it actually pulses EMI noise 'all over the place' and we are already using a radio module at least...

[argo]

Ah, gotcha!

[tigar]

the thing is: I don't need the amp for loud volume. I need it for headphones... the pwm output is pretty much uncontrollable for that... it actually pulses EMI noise 'all over the place' and we are already using a radio module at least...

what do you mean? I am using headphones. I have put in the speaker line a headphones switching socket. It works but will i have any problem using it?

[jhsa]

Are you using headphones on the module's audio output? Is there any noise? or is the audio as clear as on the speaker?
I'm asking because if the audio is clear and without noises than the speaker is loud enough for me and when too many gas planes flying around I just connect the earphone.. still have to buy one though.. or use one from an old mobile phone if I can find one..
Joao

[tigar]

I am using the headphones on the same line as the speaker. I have a socket that disconnects the speaker when the headphones plug is plugged. It is loud and clear. It only needs lower volume setting otherwise it distorts the sound and also hearts the ears. Great solution in noisy environments.

[C.João]

you should have no problems but... it better to find some ferrite beads and install them right out the sound module output.

I'm using this not only to have the sound for headphones but to get the internal beeper on the main spk and phones (and finally) getting the radio sound into my (future to be) FPV system (that could have on-plane sound and ambiance sound inputs)

you'll never know when you are called for dinner gonna get a out of control plane in the head. its best to have some feedback

[jhsa]

Yeah, forgot about the beeper.. oh well, I think i will have to make that amp anyway.. Thanks C.Joao for testing all this.. I will use the LM386 probably though..

Joao

[C.João]

well I am not but that is me and my ideas and other details. my 3W digital amp will never use its max power but it is good to have a hefty stable amp for the headphones I have other circuit though. get that amp done and report back please! (quick to)

you will have to use a POT for the beeper sound. it will sound good but to loud! (I've tested and I am really pleased with it on the speaker)