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Bell Dashboard 100, re-enter odo numbers?
On 2017-07-29 10:44, AMuzi wrote:
On 7/29/2017 11:34 AM, Joerg wrote: On 2017-07-29 09:16, AMuzi wrote: On 7/29/2017 10:19 AM, Graham wrote: "Joerg" wrote in message ... On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. [snip] No you miss my point. I am not suggesting you design/build a new unit simply knock up a simple circuit to mimic the magnet driven switch opening and closing and connect it to the appropriate terminals on the head unit. If the unit can respond to switching rates up to say 1kHz then the job should be reasonably quick and could be left to run for a known period of time to get the mileage back to where you want it. At 10m per switch cycle you would advance the reading 36kms/hr at 1hz so 100Hz which should be possible would give you 3600kms/hr 1KHz would look to be ideal as it would give you 36,000kms/hr. A bench grinder would also work with a magnet fixed to it and the sensor held next to it. That might take a good bit longer depending on the speed of the grinder. Ah, yes, clocking it all back in by pretending a 4120mi ride. Good idea. I could take an old printer motor, mout a wooden disc, glue a little magent on that and strap the whole thing into the spokes. It would probably take days though since the speedometer will peg somewhere. And eat a lot of the new battery's juice which would kind of defeat the purpose. There are sensors which can read 1720~1760rpm (grinder speeds) but a copper-steel reed switch is not one of them. Reed switches would be way too expensive for such products. It's usually just a coil. Almost has to be because it must generate a voltage that triggers the turned-off meter circuitry to turn on upon wheel rotation. Except for rare exceptions (ex: defunct Avocet), almost all bicycle computers use that type of switch to iterate wheel or crank rpm. Interesting, I didn't know that. I develop similar stuff for industrial purposes such position and rotation sensors. I'd never use Reed or anything mechanical in those, especially in an environment that is prone to vibration. Like ... a mountain bike. -- Regards, Joerg http://www.analogconsultants.com/ |
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#12
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Bell Dashboard 100, re-enter odo numbers?
On Saturday, July 29, 2017 at 7:06:59 AM UTC-7, Joerg wrote:
On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. However, I've got enough electronics projects as it is. When I am fully retired, maybe. But then I want to ride instead of build replacements for messed-up commercial designs. On the bikes I already had to do that for lighting but there it was a necessity. If I ever build my own it will be like what cars have since over 100 years. A speedometer that is backlit at night, works off the central battery and most of all never forgets its odometer info. I think that he was suggesting that you pulse the meter until it reaches the mileage you originally had. |
#13
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Bell Dashboard 100, re-enter odo numbers?
On Saturday, July 29, 2017 at 9:34:42 AM UTC-7, Joerg wrote:
On 2017-07-29 09:16, AMuzi wrote: On 7/29/2017 10:19 AM, Graham wrote: "Joerg" wrote in message ... On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. [snip] No you miss my point. I am not suggesting you design/build a new unit simply knock up a simple circuit to mimic the magnet driven switch opening and closing and connect it to the appropriate terminals on the head unit. If the unit can respond to switching rates up to say 1kHz then the job should be reasonably quick and could be left to run for a known period of time to get the mileage back to where you want it. At 10m per switch cycle you would advance the reading 36kms/hr at 1hz so 100Hz which should be possible would give you 3600kms/hr 1KHz would look to be ideal as it would give you 36,000kms/hr. A bench grinder would also work with a magnet fixed to it and the sensor held next to it. That might take a good bit longer depending on the speed of the grinder. Ah, yes, clocking it all back in by pretending a 4120mi ride. Good idea. I could take an old printer motor, mout a wooden disc, glue a little magent on that and strap the whole thing into the spokes. It would probably take days though since the speedometer will peg somewhere. And eat a lot of the new battery's juice which would kind of defeat the purpose. There are sensors which can read 1720~1760rpm (grinder speeds) but a copper-steel reed switch is not one of them. Reed switches would be way too expensive for such products. It's usually just a coil. Almost has to be because it must generate a voltage that triggers the turned-off meter circuitry to turn on upon wheel rotation. No, it has to be a switch because a coil would have ****-poor battery life. |
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Bell Dashboard 100, re-enter odo numbers?
On 2017-07-29 12:16, wrote:
On Saturday, July 29, 2017 at 7:06:59 AM UTC-7, Joerg wrote: On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. However, I've got enough electronics projects as it is. When I am fully retired, maybe. But then I want to ride instead of build replacements for messed-up commercial designs. On the bikes I already had to do that for lighting but there it was a necessity. If I ever build my own it will be like what cars have since over 100 years. A speedometer that is backlit at night, works off the central battery and most of all never forgets its odometer info. I think that he was suggesting that you pulse the meter until it reaches the mileage you originally had. Yes, I misunderstood Graham. If almost all brands contain Reed switches like Andrew said that might not be so great for the lifetime of that switch. Also, it would eat up battery because there will be a limit in the speed and I guess that's not the same at on a Ferrari Testarossa. So I'd have to let that artificial wheel run a long time in order to get the usual 4000+ miles back in, and next time 8000+, then 12000+ and so on. Most likely that takes weeks. -- Regards, Joerg http://www.analogconsultants.com/ |
#16
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Bell Dashboard 100, re-enter odo numbers?
"Joerg" wrote in message ... On 2017-07-29 12:16, wrote: On Saturday, July 29, 2017 at 7:06:59 AM UTC-7, Joerg wrote: On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. However, I've got enough electronics projects as it is. When I am fully retired, maybe. But then I want to ride instead of build replacements for messed-up commercial designs. On the bikes I already had to do that for lighting but there it was a necessity. If I ever build my own it will be like what cars have since over 100 years. A speedometer that is backlit at night, works off the central battery and most of all never forgets its odometer info. I think that he was suggesting that you pulse the meter until it reaches the mileage you originally had. Yes, I misunderstood Graham. If almost all brands contain Reed switches like Andrew said that might not be so great for the lifetime of that switch. Also, it would eat up battery because there will be a limit in the speed and I guess that's not the same at on a Ferrari Testarossa. So I'd have to let that artificial wheel run a long time in order to get the usual 4000+ miles back in, and next time 8000+, then 12000+ and so on. Most likely that takes weeks. -- Regards, Joerg http://www.analogconsultants.com/ It looks like you still have not got it. Lets forget the grinder idea as I agree with Andrew about the read switches and that does tend to rule that idea out. My first idea was to do it electronically with a simple circuit that would send relatively high frequency pulses to the appropriate terminals on the head unit to simulate the action of the switch. From your decription of your background surely this is a trivial exercise and I am sure you will have the required circuit components lying around on your bench. See my earlier posts as to how long it would take at different frquency pulsing if you set the tyre circumference to 9999mm. 4000 miles would take around 180 hours at 1Hz, 18 hours at 10Hz etc and my guess is that the head unit circuit should at least cope with that. Any higher frequecy response would be a bonus. Graham. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#17
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Bell Dashboard 100, re-enter odo numbers?
On 2017-07-29 13:46, Graham wrote:
"Joerg" wrote in message ... On 2017-07-29 12:16, wrote: On Saturday, July 29, 2017 at 7:06:59 AM UTC-7, Joerg wrote: On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. However, I've got enough electronics projects as it is. When I am fully retired, maybe. But then I want to ride instead of build replacements for messed-up commercial designs. On the bikes I already had to do that for lighting but there it was a necessity. If I ever build my own it will be like what cars have since over 100 years. A speedometer that is backlit at night, works off the central battery and most of all never forgets its odometer info. I think that he was suggesting that you pulse the meter until it reaches the mileage you originally had. Yes, I misunderstood Graham. If almost all brands contain Reed switches like Andrew said that might not be so great for the lifetime of that switch. Also, it would eat up battery because there will be a limit in the speed and I guess that's not the same at on a Ferrari Testarossa. So I'd have to let that artificial wheel run a long time in order to get the usual 4000+ miles back in, and next time 8000+, then 12000+ and so on. Most likely that takes weeks. -- Regards, Joerg http://www.analogconsultants.com/ It looks like you still have not got it. Lets forget the grinder idea as I agree with Andrew about the read switches and that does tend to rule that idea out. My first idea was to do it electronically with a simple circuit that would send relatively high frequency pulses to the appropriate terminals on the head unit to simulate the action of the switch. From your decription of your background surely this is a trivial exercise and I am sure you will have the required circuit components lying around on your bench. See my earlier posts as to how long it would take at different frquency pulsing if you set the tyre circumference to 9999mm. 4000 miles would take around 180 hours at 1Hz, 18 hours at 10Hz etc and my guess is that the head unit circuit should at least cope with that. Any higher frequecy response would be a bonus. Yeah, I could hack the cable aoart, roach on a MOSFET, wrap the whole enchilade with duct take and feed pulses from a function generator :-) I think in that case the better alternative would be to buy a better designed meter like the one I have on the MTB (Cateye Padrone) that does allow odometer re-entry. I only started this thread to see if someone knows a trick. There is a discrepancy between the Bell manual and what Bell's customer service says. The manual explicitly says you should write down the odometer value before a battery change and then re-enter it after installing a new battery. Their customer service said that it cannot be done. So one of them is wrong. -- Regards, Joerg http://www.analogconsultants.com/ |
#18
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Bell Dashboard 100, re-enter odo numbers?
On Saturday, July 29, 2017 at 10:44:08 AM UTC-7, AMuzi wrote:
On 7/29/2017 11:34 AM, Joerg wrote: On 2017-07-29 09:16, AMuzi wrote: On 7/29/2017 10:19 AM, Graham wrote: "Joerg" wrote in message ... On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. [snip] No you miss my point. I am not suggesting you design/build a new unit simply knock up a simple circuit to mimic the magnet driven switch opening and closing and connect it to the appropriate terminals on the head unit. If the unit can respond to switching rates up to say 1kHz then the job should be reasonably quick and could be left to run for a known period of time to get the mileage back to where you want it. At 10m per switch cycle you would advance the reading 36kms/hr at 1hz so 100Hz which should be possible would give you 3600kms/hr 1KHz would look to be ideal as it would give you 36,000kms/hr. A bench grinder would also work with a magnet fixed to it and the sensor held next to it. That might take a good bit longer depending on the speed of the grinder. Ah, yes, clocking it all back in by pretending a 4120mi ride. Good idea. I could take an old printer motor, mout a wooden disc, glue a little magent on that and strap the whole thing into the spokes. It would probably take days though since the speedometer will peg somewhere. And eat a lot of the new battery's juice which would kind of defeat the purpose. There are sensors which can read 1720~1760rpm (grinder speeds) but a copper-steel reed switch is not one of them. Reed switches would be way too expensive for such products. It's usually just a coil. Almost has to be because it must generate a voltage that triggers the turned-off meter circuitry to turn on upon wheel rotation. Except for rare exceptions (ex: defunct Avocet), almost all bicycle computers use that type of switch to iterate wheel or crank rpm. I could sell him my old Avocet, and he could kludge it. It seems to me like he could get a sharpie and write on the screen "+ [number of miles]." Problem solved. Or maybe put the number in his wallet on the back of a growler fill coupon -- or tattoo it to his forehead. Or, plan B, just look at his tires to see if they are worn -- or measure his chain. I suppose this would impede the completion of his definitive work on tire and chain wear rates by brand and model, but only for one wear cycle. A new chain or tire would have a new odometer reading. I don't think tires wear any faster if a bike has more or less cumulative miles, but I could be wrong about that. I had some high mile bikes that would just blow through tires. -- Jay Beattie. |
#19
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Bell Dashboard 100, re-enter odo numbers?
On Sat, 29 Jul 2017 14:48:23 -0700, Joerg
wrote: On 2017-07-29 13:46, Graham wrote: "Joerg" wrote in message ... On 2017-07-29 12:16, wrote: On Saturday, July 29, 2017 at 7:06:59 AM UTC-7, Joerg wrote: On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. However, I've got enough electronics projects as it is. When I am fully retired, maybe. But then I want to ride instead of build replacements for messed-up commercial designs. On the bikes I already had to do that for lighting but there it was a necessity. If I ever build my own it will be like what cars have since over 100 years. A speedometer that is backlit at night, works off the central battery and most of all never forgets its odometer info. I think that he was suggesting that you pulse the meter until it reaches the mileage you originally had. Yes, I misunderstood Graham. If almost all brands contain Reed switches like Andrew said that might not be so great for the lifetime of that switch. Also, it would eat up battery because there will be a limit in the speed and I guess that's not the same at on a Ferrari Testarossa. So I'd have to let that artificial wheel run a long time in order to get the usual 4000+ miles back in, and next time 8000+, then 12000+ and so on. Most likely that takes weeks. -- Regards, Joerg http://www.analogconsultants.com/ It looks like you still have not got it. Lets forget the grinder idea as I agree with Andrew about the read switches and that does tend to rule that idea out. My first idea was to do it electronically with a simple circuit that would send relatively high frequency pulses to the appropriate terminals on the head unit to simulate the action of the switch. From your decription of your background surely this is a trivial exercise and I am sure you will have the required circuit components lying around on your bench. See my earlier posts as to how long it would take at different frquency pulsing if you set the tyre circumference to 9999mm. 4000 miles would take around 180 hours at 1Hz, 18 hours at 10Hz etc and my guess is that the head unit circuit should at least cope with that. Any higher frequecy response would be a bonus. Yeah, I could hack the cable aoart, roach on a MOSFET, wrap the whole enchilade with duct take and feed pulses from a function generator :-) I think in that case the better alternative would be to buy a better designed meter like the one I have on the MTB (Cateye Padrone) that does allow odometer re-entry. I only started this thread to see if someone knows a trick. There is a discrepancy between the Bell manual and what Bell's customer service says. The manual explicitly says you should write down the odometer value before a battery change and then re-enter it after installing a new battery. Their customer service said that it cannot be done. So one of them is wrong. Early on in this thread you mentioned that you "kept a log". If so why can't you simply add the previous mileage to the present (post battery change) reading of your bike meter to get total mileage? I have an annual log application that I wrote and that is what I do. Simply enter the last year's total at the top of the new log and the computer shows the current "lifetime total". -- Cheers, John B. |
#20
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Bell Dashboard 100, re-enter odo numbers?
On Saturday, July 29, 2017 at 12:31:13 PM UTC-7, Joerg wrote:
On 2017-07-29 12:18, wrote: On Saturday, July 29, 2017 at 9:34:42 AM UTC-7, Joerg wrote: On 2017-07-29 09:16, AMuzi wrote: On 7/29/2017 10:19 AM, Graham wrote: "Joerg" wrote in message ... On 2017-07-29 02:14, Graham wrote: "Joerg" wrote in message ... Had to change the battery again on my Bell Dashboard 100 cycling speedometer. Or what they call "cycle computer" In the manual it says one can re-enter the odometer reading but nowhere it says how. When I contacted Bell years ago they said "no, you can't". Does anyone know a secret trick Bell doesn't know? I keep a log but it gets old having to calculate to see when the rear tire or other stuff is nearing end-of-life. Mainly to avoid a *KAPOW* surprise way out in the boonies. Many tires don't have TWI. -- Regards, Joerg http://www.analogconsultants.com/ Looking at your day job from the above link why not just design a circuit to replicate the job of the magnet which is only a switch which is creating a pulsed current/voltage read by the head unit electronics. Then set the tyre size to maximum and determine the maximum response frequency of the head unit circuitry and simulate pulses at that frequency. If the frequency is reasonably high it should not take too long to reset the mileage. With a tyre circumference of 9999mm, if it will take that, then you are looking at 10m per Hz. Sure I could design a meter that works better than commercial one. [snip] No you miss my point. I am not suggesting you design/build a new unit simply knock up a simple circuit to mimic the magnet driven switch opening and closing and connect it to the appropriate terminals on the head unit. If the unit can respond to switching rates up to say 1kHz then the job should be reasonably quick and could be left to run for a known period of time to get the mileage back to where you want it. At 10m per switch cycle you would advance the reading 36kms/hr at 1hz so 100Hz which should be possible would give you 3600kms/hr 1KHz would look to be ideal as it would give you 36,000kms/hr. A bench grinder would also work with a magnet fixed to it and the sensor held next to it. That might take a good bit longer depending on the speed of the grinder. Ah, yes, clocking it all back in by pretending a 4120mi ride. Good idea. I could take an old printer motor, mout a wooden disc, glue a little magent on that and strap the whole thing into the spokes. It would probably take days though since the speedometer will peg somewhere. And eat a lot of the new battery's juice which would kind of defeat the purpose. There are sensors which can read 1720~1760rpm (grinder speeds) but a copper-steel reed switch is not one of them. Reed switches would be way too expensive for such products. It's usually just a coil. Almost has to be because it must generate a voltage that triggers the turned-off meter circuitry to turn on upon wheel rotation.. No, it has to be a switch because a coil would have ****-poor battery life. Not if it's designed right and the impulse triggers a dormant circuit which then starts the whole speedometer. A pre-bias to narrow the threshold could be done with less than a micro-ampere. The downside is that is doesn't work at extremely slow wheel rotation but nobody really needs that. That does sound correct but that would mean that if you placed a magnet a little too far away from the detector, that it would have a stronger field with an increase in speed. So it would report speed at higher speed but not at lower. And that doesn't appear to be the case with any of my dozen or so speedos that I've used in the last five years. Usually you have to have the magnet almost touching the detector and at higher speeds a slightly too large a distance will cause the speedo to stop registering. For such a simple device they sure are a pain in the butt. |
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