So, I’m getting a new job, and I can no longer park my bike next to my work station.
I need to park it outside with all kinds of trash. In order for me to know when I should run out out and scream «By Ragnar’s beard!», I need to know exactly when said trash tries to steal my bike.
This is a known problem for Harley Davidson riders and they use Baby Monitors to know when someone touches their bikes. But baby monitors are designed for screaming babies, and there are a lot of things that can be more quiet than a screaming baby.
I would like to modify the baby monitor for detection of vibrations instead of screams, using a piezo microphone.
Could anyone give me a hint to increase my likelihood of success at switching out the internal microphone of a baby monitor to piezo?
I need to park it outside with all kinds of trash. In order for me to know when I should run out out and scream «By Ragnar’s beard!», I need to know exactly when said trash tries to steal my bike.
This is a known problem for Harley Davidson riders and they use Baby Monitors to know when someone touches their bikes. But baby monitors are designed for screaming babies, and there are a lot of things that can be more quiet than a screaming baby.
I would like to modify the baby monitor for detection of vibrations instead of screams, using a piezo microphone.
Could anyone give me a hint to increase my likelihood of success at switching out the internal microphone of a baby monitor to piezo?
Perhaps some other more complex solution is needed: gps tracker with sim (phone or modem), maybe dog tracking services are a good fit, second well concealed gps tracker which works only on short intervals, which is connected to its own separate small battery, camera to film someone's face who rides bike without permission, some "hard" blocking immobilizer and then some childish protection you mentioned. If you do it yourself, it will not be very expensive, if someone does it for you - that will hurt a little, but with some creativity it can be done.
Only then you can work little less stressed.
EDIT: I wrote that for the protection of the whole bike. It is WAY harder to protect pieces of the bike
Only then you can work little less stressed.
EDIT: I wrote that for the protection of the whole bike. It is WAY harder to protect pieces of the bike
You need to capture de vibrations of the bike not the sound from around. Will be more precise in detecting and not generated false alarm.
I already have GPS, but this is last resort when it is already on its way to Lithuania. Also, more entertaining to catch them in the act.
I am thinking, a thick motorcycle cover with bells attached to it will make enough vibrations for the piezo-microphone to pick up. Even when they are only after pieces of the bike.
With a regular microphone, I am afraid I will get too much background noise which will force me to shut it off at work. I need it to only react to vibrations in the frame.
I am thinking, a thick motorcycle cover with bells attached to it will make enough vibrations for the piezo-microphone to pick up. Even when they are only after pieces of the bike.
With a regular microphone, I am afraid I will get too much background noise which will force me to shut it off at work. I need it to only react to vibrations in the frame.
I use APPLE TAG's for my bike, since here in USA trash carry guns. I have one deep in the frame of the bike and the other three on valuable parts, if it moves, I can track it and let the police fight with the trash. I would be happy to fight the trash, just don't want to go to jail for "taking out the trash". It helps to have an iPhone.
Being 240Ibs, I think a tap on the shoulder would suffice. I spent 100 hours building this bike, so not going to give it away.
Apple tags work as long as you can hide them and you remove the speaker, but Apple will warn the thief that they are being followed by an airtag. Would not want to infringe on the privacy rights of criminals.
I lost one to a drug addict once, and he put it visible on wooden bridge in the forest. Even with the speaker intact, I looked for days within a 200 meter radius.
Back to my piezo mic, should I add resistance or just hope for the best? Measure the old regular microphones resistance and try to match it?
Apple tags work as long as you can hide them and you remove the speaker, but Apple will warn the thief that they are being followed by an airtag. Would not want to infringe on the privacy rights of criminals.
I lost one to a drug addict once, and he put it visible on wooden bridge in the forest. Even with the speaker intact, I looked for days within a 200 meter radius.
Back to my piezo mic, should I add resistance or just hope for the best? Measure the old regular microphones resistance and try to match it?
You can try one of these;
It's a contact exciter style speaker. You can use it in reverse as a microphone; I've done it with some success placing one on the soundboard of an acoustic guitar. No issue with low frequency / mid frequency pickup, also wont hear every little thing in the air when attached to a physical object, like a microphone would.
Of course it only works in one of 3 dimensions. There's a 3 axis accelerometer board with analog outs you could use; https://www.adafruit.com/product/163
I suppose just sum all 3 output and then any one of them's corresponding direction of movement could trigger the baby watch device.
It's a contact exciter style speaker. You can use it in reverse as a microphone; I've done it with some success placing one on the soundboard of an acoustic guitar. No issue with low frequency / mid frequency pickup, also wont hear every little thing in the air when attached to a physical object, like a microphone would.
Of course it only works in one of 3 dimensions. There's a 3 axis accelerometer board with analog outs you could use; https://www.adafruit.com/product/163
I suppose just sum all 3 output and then any one of them's corresponding direction of movement could trigger the baby watch device.
What would the accelerometer be used for?
The exciter must have a very different impedance than the microphone used on the babycall.
The exciter must have a very different impedance than the microphone used on the babycall.
So an accelerometer detects movement of a physical object. If the 3 axis one were on your bike, it could detect forward acceleration, braking, turning left and right, going uphill as distinguishable signals. If its sensitive enough, or could be made so with external circuitry, it could detect someone jiggling the handlbars and the subsequent subtle rocking of the machine on its kickstand.
The microphone in the baby monitor I assume is the most common, cheap electret, which has a bias supply that's probably AC coupled to the rest with a capacitor. The low Z of the exciter could drive the microphone input and its biasing scheme no problem; probably just need to connect the wires directly. The accel would be a bit more difficult to interface, probably have to remove the bias connection, which is likely just a resistor to +V. Then 3 reasonable value resistors like 10k to sum the 3 outputs into a single signal.
The microphone in the baby monitor I assume is the most common, cheap electret, which has a bias supply that's probably AC coupled to the rest with a capacitor. The low Z of the exciter could drive the microphone input and its biasing scheme no problem; probably just need to connect the wires directly. The accel would be a bit more difficult to interface, probably have to remove the bias connection, which is likely just a resistor to +V. Then 3 reasonable value resistors like 10k to sum the 3 outputs into a single signal.
I wonder how many physical devices have been / can be replaced with an "app"? Suppose we could start with alarm clock and calculator. Now all the way to baby (bike) monitor. As long as the battery can run the software, why not?