AiM Brake Sensor/Traqmate
10-21-2010, 08:45 PM
#16
Burning Brakes
Thread Starter
Hi Jerry,
As it turns out, the AiM sensor can easily handle unregulated source voltage varying by a significant amount - much more than your observation shows. In fact, the AiM sensor (and I assume other sensors as well) are specifically designed to handle fluctuating unregulated voltage. Here is the technical explanation directly from the MSI engineer. (very interesting - at least to me).
"... the 12V option should work just fine. Here is why.
The sensor needs an internal 6V to power both its electronics and the pressure sensing elements (silicon strain gages, in the form of a circuit called a “Wheatstone Bridge”). It would be unreasonable to expect everyone to have a regulated 6V power source to supply the sensor, so the sensor makes its own 6V power source. It does this by having a voltage regulator on-board. The regulator converts the raw, unregulated 12V source to a solid, regulated and filtered 6V to operate all the circuitry in the sensor. This voltage regulator is an LT1121 from Linear Technology (I have attached a datasheet for it, in case you are curious).
Voltage regulators, by the principles on which they operate, reject changes at their inputs (unregulated power), and give precise DC outputs. The changes in the your cars battery voltage that you were telling me about will be rejected to the extent that these changes will be suppressed by about 3000:1. So a if you had a 2V fluctuation in battery voltage, this would translate to only about a 670uV change in the 6V regulated voltage (0.01%). This rejection is termed the Line Regulation of the regulator."
Jerry, so that's why the AiM sensor ( and I assume Gary's) will work perfectly. I wish I would have known this at the beginning. But Traqmate's manual specifically states that you should not use the unregulated 12V source, and another party who I trusted was misinformed.
But all's well that ends well.
As it turns out, the AiM sensor can easily handle unregulated source voltage varying by a significant amount - much more than your observation shows. In fact, the AiM sensor (and I assume other sensors as well) are specifically designed to handle fluctuating unregulated voltage. Here is the technical explanation directly from the MSI engineer. (very interesting - at least to me).
"... the 12V option should work just fine. Here is why.
The sensor needs an internal 6V to power both its electronics and the pressure sensing elements (silicon strain gages, in the form of a circuit called a “Wheatstone Bridge”). It would be unreasonable to expect everyone to have a regulated 6V power source to supply the sensor, so the sensor makes its own 6V power source. It does this by having a voltage regulator on-board. The regulator converts the raw, unregulated 12V source to a solid, regulated and filtered 6V to operate all the circuitry in the sensor. This voltage regulator is an LT1121 from Linear Technology (I have attached a datasheet for it, in case you are curious).
Voltage regulators, by the principles on which they operate, reject changes at their inputs (unregulated power), and give precise DC outputs. The changes in the your cars battery voltage that you were telling me about will be rejected to the extent that these changes will be suppressed by about 3000:1. So a if you had a 2V fluctuation in battery voltage, this would translate to only about a 670uV change in the 6V regulated voltage (0.01%). This rejection is termed the Line Regulation of the regulator."
Jerry, so that's why the AiM sensor ( and I assume Gary's) will work perfectly. I wish I would have known this at the beginning. But Traqmate's manual specifically states that you should not use the unregulated 12V source, and another party who I trusted was misinformed.
But all's well that ends well.
10-22-2010, 10:55 AM
#18
Rennlist Member
It did work perfectly but now it has some sort of flutter going on at 0PSI that I have to compensate for in the software. I always thought it was an anomaly in the pressure reading (bounces between 25-45PSI when no brake is applied) but with all this hub-bub I think I will look at the voltage when this is happening....
10-22-2010, 12:25 PM
#20
Rennlist Member
I believe it does it all the time Kurt (motor running or not). I'll try it when I get her out for her final DE of the year tech/service. If it is (all the time), any suggestions other than looking at input voltage? It was fine the 1st year or so, just started this during this season.
10-22-2010, 02:22 PM
#21
Mr. Excitement
Rennlist Member
Rennlist Member
Check the sensor wire to see that it not pinched or the shielding compromised or grounded on both ends. The sensor could be going bad too. The fact that it flutters but still gives good readings off of 0 makes me think sensor or noise in that order. If the programing worked OK for a year or so I would first look at the wiring and device before the programing. Not an ex-purt just spit balling.
10-22-2010, 02:28 PM
#22
Rennlist Member
Check the sensor wire to see that it not pinched or the shielding compromised or grounded on both ends. The sensor could be going bad too. The fact that it flutters but still gives good readings off of 0 makes me think sensor or noise in that order. If the programing worked OK for a year or so I would first look at the wiring and device before the programing. Not an ex-purt just spit balling.
