Timeline for MOSFET outputting bad waveform
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 29, 2021 at 14:39 | answer | added | Daniel Melendrez | timeline score: 1 | |
| Apr 29, 2021 at 14:15 | comment | added | Marcus Müller | @aconcernedcitizen is right, if you don't actually want to build a very custom power supply, but just need to produce a constant, predictable voltage, a switch-moder boost converter is the way to go (or an inverting converter), and the ASICs for these are very well-designed, and cheap, and high-frequency, allowing you to reduce the size, cost and amount of passives necessary to generate a clean HV. | |
| Apr 29, 2021 at 14:10 | comment | added | a concerned citizen | Why not use a dedicated IC? They will outperform uCs. That 100n cap in the gate doesn't seem to be a sensible choice for speed. | |
| Apr 29, 2021 at 14:00 | comment | added | franfio8 | @MarcusMüller thanks for the advice. As the project is a Geiger counter, a microcontroller is probably the way to go. | |
| Apr 29, 2021 at 13:48 | review | Close votes | |||
| May 14, 2021 at 3:02 | |||||
| Apr 29, 2021 at 13:43 | comment | added | franfio8 | @SpehroPefhany ok so I removed the 10nF and I get a square wave but it signal is still not clean. | |
| Apr 29, 2021 at 13:43 | comment | added | Marcus Müller | Friendly reminder that trying to use a 555 in a HV power supply sounds like a recipe for pain. You'll find that every, even the cheapest, microcontroller excels very much as PWM controller, and that many modern microcontrollers are basically "power supply and motor control ASICs with a bit of programmable controller" more than anything else – this isn't a job for a 555, but for a microcontroller, IMHO. | |
| Apr 29, 2021 at 13:38 | comment | added | Spehro 'speff' Pefhany | Maybe you should favor us with a photo of your setup. You should have a capacitor across the 12V supply near the 555 (eg. 100uF). The 10n capacitor won't do anything good there, it should eliminate everything across the load after the first pulse. | |
| Apr 29, 2021 at 13:35 | comment | added | franfio8 | @SpehroPefhany well at the moment the load is just a 10kOhm resistor and the capacitor is a 10nF ceramic to block any DC but the signal is the same before the cap, with a smaller load and without a load. | |
| Apr 29, 2021 at 13:34 | comment | added | Unimportant | Why the 1:2 voltage divider and capacitor on the gate? It slows down transition time and does not turn on the MOSFET as hard as it could be. How is the capacitor in series with the load supposed to be discharged each cycle? | |
| Apr 29, 2021 at 13:28 | comment | added | Spehro 'speff' Pefhany | What exactly is the nature of the load during this test? I presume that that unmarked capacitor on the drain in your schematic is not present? | |
| Apr 29, 2021 at 13:27 | review | First posts | |||
| Apr 29, 2021 at 15:52 | |||||
| Apr 29, 2021 at 13:24 | history | asked | franfio8 | CC BY-SA 4.0 |