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| AC Rectified - DC Mosfet dimmer - Hints please |
| (1/7) > >> |
| bingo600:
I was thinking about using this AC rectified DC-dimmer http://www.instructables.com/id/AC-PWM-Dimmer-for-Arduino/ BrianHG writes here --- Quote from: BrianHG on February 28, 2017, 01:20:54 pm --- Now, I have a method using a power mosfet and AC-DC bridge rectifier, but, it's something like a 10 component solution and you need to switch the optocoupler on only during the 0 crossing phase of the AC & you also need both access to the hot and neutral. --- End quote --- Would that apply to this construction (switching of the opto during zero cross) ? I mean it's not AC anymore , but "unfiltered DC" /Bingo |
| bingo600:
I'll be dimming 2 x 40w - lightbulbs (The big ballon ones with golden glow) I have gotten both some Mosfets : STB10NK60Z - http://www.st.com/resource/en/datasheet/stb10nk60z.pdf And some IGBT's : SGP10N60 - https://www.digchip.com/datasheets/parts/datasheet/216/SGP10N60-pdf.php 100uF will be - NIPPON CHEMI CON series KMX 100uF 400V super LONG LIFE capacitors 105'C And i have some 4N25 Optos in the drawer. The author says the IGBT's are probably the best for this , but Mosfets are ok. I don't have much experience with Mosfets or IGBT's , but i do with mains (no worries there). MCU would be a ESP8266 , where i'll adapt the opto resistor to 3.3v Can anyone see problems with the circuit , besides missing a fuse ? /Bingo |
| bingo600:
The ESP8266 is going to need 3.3v anyways , so if i get a 230->12v PSy , and a DC-DC switcher for the 12 -> 3.3v Could i get rid of the Capacitive PSU , i mean the 100uF cap & diode. And put the 12v psu in use for driving the Fet/IGBT ? I'll loose the galvanic isolation , but the IF is going to be wireless via the ESP , so i'm not too worried. Unless the "shared ground "Unsmooted 400v DC Ground" , and 12v DC-DC converter ground would intefere. Any hint for what to modify ? I mean i suppose i still need to have a pullup in the FET gate , as the opto is the "pulldown" Do i need some 400v cap on the "mains (load) DC" ? - For smoothing ? As i see it on the existing schmatic , there isn't any on the one in the picture, due to the diode. A few hints would be appreciated. /Bingo |
| Benta:
That circuit has so many dumb things, it's difficult to know where to start (is "instructables" really like that? I've never visited them). First: if you switch off your Arduino, the lamps will be lit always. If you decide that the "always on" functionality is OK, then: There's absolutely NO reason to use a 400 V cap. The cap will work just a well connected to the junction of R4/R5, so a 25 V type is enough. D5 is unnecessary. Reduce R5 to 5k6 Place a resistor between R4/R5 and the 4N35 Use a high-voltage resistor for R4, eg, VR68 from Vishay. That's just a start... |
| bingo600:
--- Quote from: Benta on March 02, 2017, 08:16:42 pm ---That circuit has so many dumb things, it's difficult to know where to start (is "instructables" really like that? I've never visited them). --- End quote --- Thanx for the comments I knew about the PWM source must be always on Author mentions this circuit (other creator) , and says it has some bad design faults , explains on Instructables page He modified it , and says this is better Unfortunately i'm an "Analog noob" , and "have to trust" the designers , that's why i asked for some hints (review) It will be in my summerhous , and i don't want a fire :scared: /Bingo |
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