inline volume controller

[Tomcat48]

Can I install a inline automatic volume limiter in line to external speaker?

 

[Ubbe]

Try an an old fashion light bulb in series. When the voltage to the speaker increases the resistance in the bulbs filament increases and will reduce the level to the speaker. Try something like 6V and 5W or lower wattage. It will only give half power to the speaker at best so the volume needs to be cranked up.

The speaker amplifier are short circuit and over temp protected so you could use diodes over the speaker cables plus and minus. Three diodes in series and then three other diodes in series but turned the other way around. Then the signal can't go over +2V and -2V. Diodes need to be of the 1N4001 kind or higher current capable. When the diodes clip the signal it becomes a square wave and may sound louder to your ears than when not clipped. Maybe include that light bulb between the scanner and diodes as the best combined solution.

/Ubbe

 

[Tomcat48]

Maybe I did not phrase my question properly. I meant I am trying to keep from having extreme modulation from different scans. There are automatic volume devices and I was wondering if I could install one of these without harming my BCD536HP scanner? I mean between my scanner and external speaker.

 

[Ubbe]

It will not harm the 536, it is short circuit protected if you make a mistake. Do you have a link to the devices you are thinking of using?

A light bulb are an automatic volume leveler. When the volume increase it reduces the signal. If the light bulb are 5 ohm while cold it will be something like 15 ohm or more when it lights up and if you have that in series with one speaker lead it will regulate the audio level. Other than that you will need a speaker that has it's own powered amplifier that has a limiter function.

One amplifier IC for $2 seems to be suitable to use if anyone have made an external speaker amplifier with that IC.

The TPA2029D1 is a mono, filter free Class-D audio Filter Free Class architecture power amplifier with dynamic range compression 3W into 4Ω at 5V (10%THD+N) (DRC) and automatic gain control (AGC)

/Ubbe