Timeline for pull up or pull down resistor for optocoupler
Current License: CC BY-SA 4.0
21 events
| when toggle format | what | by | license | comment | |
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| Nov 10, 2018 at 2:00 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| May 29, 2018 at 17:47 | comment | added | ETeddy | I studied SSR choice for a moment but for two major reasons I thought I cannot use it: 1: It is expensive 2: And more important, It seems cannot use it with 490Hz PWM of arduino. | |
| May 29, 2018 at 17:04 | answer | added | drtechno | timeline score: 1 | |
| May 29, 2018 at 16:21 | comment | added | drtechno | Before I start on an awnser, did you try using an SSR? | |
| May 29, 2018 at 15:46 | answer | added | Spehro 'speff' Pefhany | timeline score: 1 | |
| May 29, 2018 at 7:37 | comment | added | ETeddy | according to the datasheet above 70 c the Rated Load of resistor begin to decrease until 155 c which Rated Load become 0. | |
| May 29, 2018 at 7:33 | comment | added | user133493 | And what does the datasheet for your resistor give as the expected rise above ambient for that power? | |
| May 29, 2018 at 7:28 | comment | added | ETeddy | suppose the max voltage 330v. By usin 2 resistors in series each resistor's voltage should be 165v then the power dissipation 272mW! | |
| May 29, 2018 at 7:25 | comment | added | Neil_UK | Your resistor will be dissipating 1W. That means as a 1W resistor, it will get very hot. Depending on how the resistor is rated, perhaps 200C. It's designed to. Some reference temperatures - 40C feels warm to hot, 60C can touch, but can't hold finger on, 80C max for radiators can touch briefly without harm, 100C boiling water temperature causes harm to touch, 200C rated running temperature of some high power resistors. | |
| May 29, 2018 at 7:23 | comment | added | Maple | At 3mA you are basically at the maximum dissipation capacity of the resistor. Awful. You basically made yourself mini space heater, not dimmer. | |
| May 29, 2018 at 7:22 | comment | added | ETeddy | Even I tried it with 2 100k resistors in series but that didnt solve the problem. | |
| May 29, 2018 at 7:20 | comment | added | ETeddy | This is the raw circuit and the fuse will be placed at last, but consider that it is used to dim a 15W incandescent lamp so what is the problem with 100k resistor? | |
| May 29, 2018 at 7:13 | comment | added | Maple | I don't like this circuit. By connecting D1 to top joint of the bridge one can cut the dissipated power in half right away. Not to mention all the safety concerns @replete point out. | |
| May 29, 2018 at 7:13 | comment | added | user133493 | I repeat, are you touching R1 while the circuit is live, or while C1 is charged? If this circuit is connected directly to the mains then it is rubbish. There isn't even a fuse. If you expect 330V across R1 then what is V^2 / R? | |
| May 29, 2018 at 7:10 | comment | added | ETeddy | BR1 is converting AC main (220 Vac) to full-waved DC. It seems the max voltage made by C1 should be 310 to 330 V so 100k 1W resistor should be okay. but the problem is about the current when optocoupler shorts the circuit. | |
| May 29, 2018 at 7:01 | comment | added | user133493 | You were touching the circuit during operation? This circuit is powered from the line, right? Please give more information about what BR1 is connected to. If you're disconnecting the circuit before touching the part, I also hope you understand the danger from C1. | |
| May 29, 2018 at 6:56 | comment | added | ETeddy | I couldnt touch it after few seconds! | |
| May 29, 2018 at 6:54 | history | edited | winny | CC BY-SA 4.0 |
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| May 29, 2018 at 6:50 | comment | added | user133493 | How hot? How did you measure it? Warming up is part of a resistor's life. It would be good to give values of the other components used or to link the instructable. | |
| May 29, 2018 at 6:47 | review | First posts | |||
| May 29, 2018 at 6:54 | |||||
| May 29, 2018 at 6:44 | history | asked | ETeddy | CC BY-SA 4.0 |