| ??? 07/25/06 13:47 Read: times |
#121023 - what about a zener across the RTD? Responding to: ???'s previous message |
The circuit uses a constant current source built around LM358 and the voltage developed across the RTD is then amplified by using 3 Amp classic Instrumentation amplifier. With this configuration the output is 1V to 3V. The problem arises when there is no RTD connected in the system as it opens up the feedback of the LM358 current sources causing the output to become Max Swing 13V.
A current devider cant work as it will do more bad than good it does as it will cause my useful signal to reduce in magnitude. what about a zener across the RTD?, it will be 'infinite resistance' when a RTD is installed and clamp the volatge when none is present. Erik |
| Topic | Author | Date |
| Reistor in series in signal from Amp to ADC. | 01/01/70 00:00 | |
| You forgot the other Question | 01/01/70 00:00 | |
| Read the app notes | 01/01/70 00:00 | |
| What ADC? What application? | 01/01/70 00:00 | |
| Re: Application. | 01/01/70 00:00 | |
| That's not good | 01/01/70 00:00 | |
| a much more elaborate protection scheme must be im | 01/01/70 00:00 | |
| Re: RTD & high voltage output. | 01/01/70 00:00 | |
| what about a zener across the RTD? | 01/01/70 00:00 | |
| Some questions | 01/01/70 00:00 | |
| ADC details? | 01/01/70 00:00 | |
| datasheet does not contain because | 01/01/70 00:00 | |
| ADC details still missing! | 01/01/70 00:00 | |
| Yes ADC details Missing,. | 01/01/70 00:00 | |
| That's what we need the details for... | 01/01/70 00:00 | |
| what detail? | 01/01/70 00:00 | |
| Analog input circuitry and timing diagram | 01/01/70 00:00 | |
| Forum Power. | 01/01/70 00:00 | |
| Link? | 01/01/70 00:00 | |
| Re Link. | 01/01/70 00:00 | |
| if you use them, sign up | 01/01/70 00:00 | |
Thanks | 01/01/70 00:00 |