| ??? 03/21/05 17:53 Read: times |
#90163 - Oscillations... Responding to: ???'s previous message |
These nasty oscillations of battery powered circuits can very often be observed, not only in digital applications. If you have, for instance, a battery powered music amplifier to drive a little speaker, then low frequency oscillations (very characteristic 'pumping') can occur, if impedance of power supply increases. This increase often takes place if the battery becomes a bit older. In such applications bypassing the battery with a big electrolytic is a must!
Another unwanted performance can be observed, when in a battery powered circuit two or more oscillators of different frequencies exist. What works perfect when being powered by a voltage regulator in laboratory, can heavily fail, when running the same circuit by batteries: The oscillators can lock, means, they still oscillate, but no longer at different frequencies... In such applications, where a voltage regulator cannot be used, an oscillation methode must be choosen, which does not introduce noise (spikes e.g.) on supply voltage. So, a ICL7555 decoupled with a RC filter should be preferred instead of a Schmitt trigger oscillator using a 74HCMOS gate, then. Kai |
| Topic | Author | Date |
| LPC932 Oscillating | 01/01/70 00:00 | |
| scope | 01/01/70 00:00 | |
| Scope | 01/01/70 00:00 | |
| BIG electrolytic | 01/01/70 00:00 | |
| Bypass where | 01/01/70 00:00 | |
| Diode ? | 01/01/70 00:00 | |
| No I do not | 01/01/70 00:00 | |
| flywheel diode | 01/01/70 00:00 | |
| Freewheeing Diode | 01/01/70 00:00 | |
| Holy Cow | 01/01/70 00:00 | |
| More Explosions | 01/01/70 00:00 | |
| flywheel | 01/01/70 00:00 | |
| Thank you all! | 01/01/70 00:00 | |
| Flywheel | 01/01/70 00:00 | |
| flywheel. | 01/01/70 00:00 | |
| battery | 01/01/70 00:00 | |
| Did not work | 01/01/70 00:00 | |
| try both LF and HF | 01/01/70 00:00 | |
| 3.3 amd 6.6 | 01/01/70 00:00 | |
| Thats it | 01/01/70 00:00 | |
| LM2937 | 01/01/70 00:00 | |
| what is solarbotics | 01/01/70 00:00 | |
| Excellent | 01/01/70 00:00 | |
| Battery | 01/01/70 00:00 | |
| Simple RC-filters might help | 01/01/70 00:00 | |
| Diode 1N4000 | 01/01/70 00:00 | |
| Will not help | 01/01/70 00:00 | |
| Got it. | 01/01/70 00:00 | |
| Answer needed, please | 01/01/70 00:00 | |
| Whoops! | 01/01/70 00:00 | |
| You don't know the currents?????? | 01/01/70 00:00 | |
| Current ? | 01/01/70 00:00 | |
Found out what currents are flowing? | 01/01/70 00:00 | |
| nope | 01/01/70 00:00 | |
| Ok | 01/01/70 00:00 | |
| Diode type | 01/01/70 00:00 | |
| Oscillations... | 01/01/70 00:00 | |
| aka | 01/01/70 00:00 | |
| Exactly! | 01/01/70 00:00 |