| ??? 05/23/06 18:53 Modified: 05/23/06 18:54 Read: times |
#116968 - Have you examined the linear PS? Responding to: ???'s previous message |
Have you correctly applied the 7805? Are you sure?
Is there an appropriately sized (8000uF/AMP, per NSC) filter capacitor on the rectifier output? Is there an adequate (~2.2 uF per NSC)output cap? Have you examined the output with an oscilloscope? Have you examined the output from the linear supply with a voltmeter? First of all, under no load: What's the DC voltage? What's the AC component on the output? How do these things differ when a purely resistive load, e.g. a 1-ohm, > 5-Watt resistor, is applied? How does the linear supply's behavior differ, under these same conditions, from that of the SMPS? If you can't answer these questions, you've got some work to do. I've been using the 7805 and equivalents since it was brand-new on the market, and never, Never, NEVER had one fail to produce a useable 5-volt regulated supply. RE |
| Topic | Author | Date |
| smps/linear ps. | 01/01/70 00:00 | |
| the moon is in the 3rd quarter | 01/01/70 00:00 | |
| Post circuit diagram | 01/01/70 00:00 | |
| Break of GND line? | 01/01/70 00:00 | |
| Maybe he's forgotten the caps? | 01/01/70 00:00 | |
| Any connection to Phone line ? | 01/01/70 00:00 | |
| Have you examined the linear PS? | 01/01/70 00:00 | |
| one caveat | 01/01/70 00:00 | |
| granted, but that's a misapplication. | 01/01/70 00:00 | |
| his question is why does it fail with 78 | 01/01/70 00:00 | |
| True enough, but until he does the work | 01/01/70 00:00 | |
| as usual | 01/01/70 00:00 | |
| Natural enemy | 01/01/70 00:00 | |
| Quite true, Kai | 01/01/70 00:00 | |
| You are experienced, I see... | 01/01/70 00:00 | |
| I just wonder | 01/01/70 00:00 | |
| When I need a clean signal | 01/01/70 00:00 | |
| but then you have to clean up | 01/01/70 00:00 | |
| Fuse in secondary circuit. | 01/01/70 00:00 | |
| Fuses | 01/01/70 00:00 | |
| Slow-blo? | 01/01/70 00:00 | |
Yes, but... | 01/01/70 00:00 | |
| schematic | 01/01/70 00:00 | |
| no schematic here ... ??? | 01/01/70 00:00 |