| ??? 12/15/05 02:44 Read: times Msg Score: +1 +1 Informative |
#105255 - The heater heats up and heats up and ... Responding to: ???'s previous message |
Mehdi said:
But i don't know if it is isolated from shield too! Can you check it? The sensor is between ground and adc-input,A 10k res is between adc-input and vcc,and there is a 10uF tantal between adc-input and ground. Is it enough? To improve the resistance against cell phone radiation you should add a ferrite bead of about 1µH (estimated from low frequency performance) and a second 10µF cap between your 10µF tantal and input of ADC. Do also add a decoupling capacitor where the 10k resistor is connected to Vcc. ESD is bestly fighted against by the help of two cera diodes or transzorbs or 10nF caps connected from each sensor line to enclosure, right where the sensor cable enters the enclosure. when i attach 2 sensor,after 2 minutes i take temperature from both of them,they are equal always Of course, when everything works fine. But what if the tape which "glues" the sensor to skin does not make its job properly after some hours? Then, temperature of sensor decreases, your device thinks the baby becomes colder and the heater heats up, and heats up and heats up... A second skin temperature sensor would allow you to detect this failure, by simply comparing the two sensor readings: If there's a relevant difference, an alarm is invoked! Kai |
