ISD1820 distortion / put sound on device

Audioguru again

Joined Oct 21, 2019
3,017
The CR2032 battery is too small to produce 1/2W of audio power. It is designed for powering a circuit with an LCD display (like a weighing scale) operating at 1/100th the current the recording module uses when playing back a voice. Use 3 AAA or AA alkaline battery cells (4.5V when new) instead.

The sound will be very distorted if you record it and/or play it back louder than the amplifier can produce.

The speaker must be 8 ohms because the peak output power is determined by the battery voltage times the speaker current. A 50 ohm speaker will sound like an earphone with 1/6th the power.

The tiny speakers you show will sound tinny and make a male voice sound like a chipmunk. A clock radio speaker is usually 3" in diameter.
A speaker needs to have a suitable enclosure.
 

KMoffett

Joined Dec 19, 2007
2,918
As I recall the time was 10Sec max, so the sample rate was 6.4KHz. Maybe slightly better if the sample rate was 8KHz. But I didn't want to mess with surface mount resistors. Even talking in a low pitch voice didn't help.
 

Audioguru again

Joined Oct 21, 2019
3,017
The most frequent phrase spoken on an old telephone (2.7kHz to 3kHz cutoff) is, "What? What did you say?" over and over because the important consonant sounds of speech that reach 14kHz are missing and muffled. Consonants produce intelligibility.
Do you talk in only vowels like a pig? No.

Was the output level too high causing clipping?
Was the input level to the mic so loud it caused the distortion?
 

Thread Starter

mak99

Joined Sep 14, 2020
21
I recently bought two recorder/playback PCBs with an ISD1810 chip. The playback sound was really crappy. Same with both boards. Tried different voltages and many different speakers. No improvement, only louder, crappy sound. :( I finally ordered a board with a ISD-COB-17240 from Digikey. It is great.
That is to bad, but i actually think the ISD1820 are really good, the sound are good and when the battery is not drained, there is no static/distortion what so ever. for the priceof 1.2 euros i think it is doing really good
 

Thread Starter

mak99

Joined Sep 14, 2020
21
The most frequent phrase spoken on an old telephone (2.7kHz to 3kHz cutoff) is, "What? What did you say?" over and over because the important consonant sounds of speech that reach 14kHz are missing and muffled. Consonants produce intelligibility.
Do you talk in only vowels like a pig? No.

Was the output level too high causing clipping?
Was the input level to the mic so loud it caused the distortion?
Do not know if this is focused towards me or the other guy. But the battery was the problem in my case
 

Thread Starter

mak99

Joined Sep 14, 2020
21
Do any of you who helped me with the problem know, if it is possible to pre record a soundfile on the computer and somehow get it on the ISD1820?
 

ericgibbs

Joined Jan 29, 2010
12,583
hi mak,
The method use is to download an audio track from the web, play it back thru my PC speakers and place the ISD1820 close to the speaker.
Works fine, you may have to play with the sound levels in order to get the result you want.
I would suggest you try a decent 8 ohm speaker, you will be surprised at the improved sound quality.

E
 

Thread Starter

mak99

Joined Sep 14, 2020
21
hi mak,
The method use is to download an audio track from the web, play it back thru my PC speakers and place the ISD1820 close to the speaker.
Works fine, you may have to play with the sound levels in order to get the result you want.
I would suggest you try a decent 8 ohm speaker, you will be surprised at the improved sound quality.

E
Okay i will give that a try then. Yeah I thought about doing that, but lets say i am gonna make 100's of them. the speaker cant be to expensive. And the speaker i already have is a 8Ohm speaker 0.5 A
 

Thread Starter

mak99

Joined Sep 14, 2020
21
The CR2032 battery is too small to produce 1/2W of audio power. It is designed for powering a circuit with an LCD display (like a weighing scale) operating at 1/100th the current the recording module uses when playing back a voice. Use 3 AAA or AA alkaline battery cells (4.5V when new) instead.

The sound will be very distorted if you record it and/or play it back louder than the amplifier can produce.

The speaker must be 8 ohms because the peak output power is determined by the battery voltage times the speaker current. A 50 ohm speaker will sound like an earphone with 1/6th the power.

The tiny speakers you show will sound tinny and make a male voice sound like a chipmunk. A clock radio speaker is usually 3" in diameter.
A speaker needs to have a suitable enclosure.
Do you think this would be to much? a double cell buttoncell battery holder or will the 6V cause any issues?

https://www.ebay.com/itm/5Stks-Case...561523?hash=item3d67dd4d33:g:ipoAAOSwllpbFKkN
 

Audioguru again

Joined Oct 21, 2019
3,017
You need a battery that produces enough current. Two small battery cells in series produce the same weak current as one cell but twice the voltage.
The datasheet of a Name-Brand (not a Chinezium one) CR2032 battery cell says it is designed for a current of only 0.19mA. But the voice recording IC uses a current of 167mA when it produces an output power of 0.5W.
167/0.19= 879 times more current. The battery datasheet says it can produce 6.8mA for 2 seconds, 12 times each day for a few days.
EDIT: The max supply voltage is only 4.5V.
 
Top