Speaker Replacement for Radar Detector:

Thread Starter

Defcon 1

Joined May 18, 2020
11
Hello and Good Day,

I wanted to see if I could replace/upgrade my radar detectors audio speaker. It is really old and the sound is weak, but I really like the unit and it functions perfectly outside of the tune being low. I believe the speaker is the black cylinder unit on the right hand side, (I think that's what the "SP1" designation on the circuit board means???). Could I replace that with an 8 ohm low watt micro/mini speaker? Should I replace it with the same unit that is on there? I don't know the specs on the current speaker, but it is a 12v power source so can I just de-solder and solder in another one?

Not too tech savy when it comes to this stuff so I'm all ears for opinions and suggestions, thank you.

Pic files attached for reference:
 

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dl324

Joined Mar 30, 2015
10,736
Could I replace that with an 8 ohm low watt micro/mini speaker? Should I replace it with the same unit that is on there? I don't know the specs on the current speaker, but it is a 12v power source so can I just de-solder and solder in another one?
You can't replace the speaker with a different part unless you understand what the circuit was designed to drive. Most likely, substituting an 8 ohm speaker won't work.

Your pictures aren't helpful. We need a part number for the speaker and a schematic of the circuitry involved.
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
Your pictures aren't helpful. We need a part number for the speaker and a schematic of the circuitry involved.
Oh boy I don't even know where to begin with that, I do have a users manual but it doesn't show any detailed diagrams or schematics of the detector, just the basics like function and power requirement. I might be able to request one but I'm sure that's confidential information from the company. There is no visible P/N or markings on the speaker either other than the + / - identifiers.

Would a new speaker simply not work due to the power requirements or are you saying it could damage the assembly if I tried? (I.E. I can uninstall / (reinstall if failed) the original speaker and attempt a different one?)
 

dl324

Joined Mar 30, 2015
10,736
Would a new speaker simply not work due to the power requirements or are you saying it could damage the assembly if I tried?
What you're proposing to do makes no sense. The circuit was designed for a specific sound element. It's unlikely they would design the circuit in such a way that anyone could substitute whatever they wanted for the original part.

If no schematics are available, you can trace the circuitry around the speaker.
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
What you're proposing to do makes no sense. The circuit was designed for a specific sound element. It's unlikely they would design the circuit in such a way that anyone could substitute whatever they wanted for the original part.
I'm thinking that the audio portion of the circuit board isn't it's primary function, the radar/IR function is, and the speaker is just like an "annunciation" to sync with the LED lights to beep when prompted. That's my train of thought to why I'm asking these questions, I'm not trying to redesign the board, but substitute/replace the speaker so I can hear the beeps better. I know the board is very complex, but most of that complexity I assume is for the function of the detection elements.

Have you ever seen a speaker like that though? Cylinder type? I don't even know where to begin to look for something like it, because I'm not familiar with the nomenclature of circuity and components. Thanks for your input thus far btw.
 

MrChips

Joined Oct 2, 2009
21,112
That "speaker" looks like a piezoelectric buzzer.

There are two kinds:
1) a passive piezoelectric transducer that requires an AC signal to produce a sound
2) a piezoelectric buzzer that has built-in oscillator circuit and only needs a DC voltage to emit a sound.

Let us see the face of the buzzer. If it is sealed you can cut a hole in the face to let the sound out.
 

MrSoftware

Joined Oct 29, 2013
1,778
As mentioned above, the first task is to figure out if that is really a "speaker" at all, or if it's a piezo element. These are 2 very different things, both are used to make sound. Look very carefully all around the part to see if you can find any numbers or markings of any kind. If you can identify the exact part then that would make the task of considering a replacement 100% easier.
 

Audioguru again

Joined Oct 21, 2019
1,483
Should we stop talking about an illegal radar detector? He can't hear it because he is illegally driving too fast? Or he can't hear it because his car had its muffler illegally removed? Both?
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
Should we stop talking about an illegal radar detector? He can't hear it because he is illegally driving too fast? Or he can't hear it because his car had its muffler illegally removed? Both?
Lol they are not illegal in my state, and it's for my Jeep 4-cylinder, which maxes out at 50 mph on 35" tires, so no driving fast here for me lol.
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
That "speaker" looks like a piezoelectric buzzer.

There are two kinds:
1) a passive piezoelectric transducer that requires an AC signal to produce a sound
2) a piezoelectric buzzer that has built-in oscillator circuit and only needs a DC voltage to emit a sound.

Let us see the face of the buzzer. If it is sealed you can cut a hole in the face to let the sound out.
Ok great I will take another look tomorrow and post more pictures. I'm sure it's DC because it's powered by the vehicle cigarette lighter and they are 12 VDC. I think the detector is too small to have a inverter installed on the circuit board to change it to AC.
 

dl324

Joined Mar 30, 2015
10,736
Lol they are not illegal in my state, and it's for my Jeep 4-cylinder, which maxes out at 50 mph on 35" tires, so no driving fast here for me lol.
Then why bother using it? It won't work for LIDAR. Just drive the speed limit and you don't need to worry.
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
Then why bother using it? It won't work for LIDAR. Just drive the speed limit and you don't need to worry.
I have my reasons:) None of them have to do with speeding. Just want to get it back up and running so I can hear it again, it's a good piece of equipment.
 

dl324

Joined Mar 30, 2015
10,736
I have my reasons:) None of them have to do with speeding. Just want to get it back up and running so I can hear it again, it's a good piece of equipment.
Okay. Police have gotten sneakier in trying to catch speeders. They hide out of sight or off to the side so detectors can't pick them up.

Trace the circuitry around the existing sound element so we can see how it's being driven.
 

Audioguru again

Joined Oct 21, 2019
1,483
All amplifiers produce an AC output to a speaker. A little piezo sounder can be either a transducer (speaker driven by an AC sound) or be a beeper with a built-in oscillator that is powered by DC.

35" wheels on a little Fiat-Jeep? If it is driving its max of 50mph in my neighbourhood that has 30mph signs then of course it is illegal.
Recently the local police caught a 16 years old kid with a learner's permit driving his mother's Mercedes at about 202mph. The police chased him without using radar.
 

MrChips

Joined Oct 2, 2009
21,112
Ok great I will take another look tomorrow and post more pictures. I'm sure it's DC because it's powered by the vehicle cigarette lighter and they are 12 VDC. I think the detector is too small to have a inverter installed on the circuit board to change it to AC.
That is not correct. You misunderstand. You are thinking about AC that comes out of your wall socket.
In electronics there are all sorts of different kinds of AC voltages.
Even though your smart phone is powered off a DC battery, it picks up AC signals from the cellular tower.
All speakers such as those in your smart phone, car radio, stereo, etc. require AC signal to drive the speaker otherwise there would be no sound output.

Your radar detector has a "speaker". The diaphragm in the speaker has to vibrate in order to produce a sound. To do this it needs AC. This AC signal is generated in the radar unit itself or it is generated in the "speaker" using DC voltage going into the "speaker".
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
Trace the circuitry around the existing sound element so we can see how it's being driven.
Will do, I'll try my best and have better pictures available.

All amplifiers produce an AC output to a speaker. A little piezo sounder can be either a transducer (speaker driven by an AC sound) or be a beeper with a built-in oscillator that is powered by DC.
Interesting, thanks for the info. Also while I remember, the piezo only makes like 3 different kind of beeps, (3 different tunes), not sure if that helps but just wanted to through that out there.

That is not correct. You misunderstand. You are thinking about AC that comes out of your wall socket.
In electronics there are all sorts of different kinds of AC voltages.
Even though your smart phone is powered off a DC battery, it picks up AC signals from the cellular tower.
All speakers such as those in your smart phone, car radio, stereo, etc. require AC signal to drive the speaker otherwise there would be no sound output. Your radar detector has a "speaker". The diaphragm in the speaker has to vibrate in order to produce a sound. To do this it needs AC. This AC signal is generated in the radar unit itself or it is generated in the "speaker" using DC voltage going into the "speaker".
Oh man this is a lot more complicated than I thought lol. Very good information thank you. I am familiar with using a Multimeter so would I be able to confirm the type of voltage going into the Piezo by probbing the power prong on it?
 

Audioguru again

Joined Oct 21, 2019
1,483
A DC piezo beeper does not play a tune that has different frequencies, it always beeps only one frequency.
An AC piezo transducer can play a tune with many frequencies, but it might also have some DC on it which does nothing.
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
A DC piezo beeper does not play a tune that has different frequencies, it always beeps only one frequency.
An AC piezo transducer can play a tune with many frequencies, but it might also have some DC on it which does nothing.
Does the differences in applied voltage give the AC Piezo it's different sounds? It has 3-4 clearly distinct sounds. I am familiar with a multimeter, is it possible to measure the voltages at all the different tunes to see what kind of Piezo it (generally) is? No part-numbers anywhere on it.
 

MrSoftware

Joined Oct 29, 2013
1,778
Changing the frequency will change the pitch, changing the voltage will change the volume. You can try a multi meter to see if it will give you any peak voltage readings, but I suspect you're going to need an oscilloscope to get anything really useful. BUT a piezo looks similar to a capacitor electrically, so use your multi-meter to measure the resistance across the pins. You can try it with the device in-circuit. If you get a high impedance, say 1k or more, then it's a piezo. If you get something lower like 16-ohms or lower then it might be a speaker, you would need to remove it from the circuit and measure again to say for sure as something else in the circuit could be lowing the impedance.
 

Thread Starter

Defcon 1

Joined May 18, 2020
11
Changing the frequency will change the pitch, changing the voltage will change the volume. You can try a multi meter to see if it will give you any peak voltage readings, but I suspect you're going to need an oscilloscope to get anything really useful. BUT a piezo looks similar to a capacitor electrically, so use your multi-meter to measure the resistance across the pins. You can try it with the device in-circuit. If you get a high impedance, say 1k or more, then it's a piezo. If you get something lower like 16-ohms or lower then it might be a speaker, you would need to remove it from the circuit and measure again to say for sure as something else in the circuit could be lowing the impedance.
Ok great, I'll give that a go too. There is a volume control (rheostat?) in the circuit that is changeable by rotating the disk, so I will measure the peak voltage and then the resistance at the highest volume setting.
 
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