456:, assuming that voltage and frequency remain constant. The LEDs are connected in parallel with the 10 μF electrolytic filter capacitor. There are four parallel branches, each having 12 LEDs in series; these branches consume about 20 mA each, or 4 x 20 = 80 mA total. The diodes limit the voltage to about 40 V per branch. Since normally the circuit is connected directly to the mains network without galvanic isolation, a
17:
473:
255:
363:
447:
151:
74:
in all places where a person could come into electrical contact with it. In addition, failure of a single component can result in unacceptably high voltages at the output. For instance, if the
269:
372:
510:
70:
between the input and output, which means the output side is a dangerous shock hazard. For safety reasons, this type of power supply and every circuit connected to it must be
452:
Analyzing the circuit of the lamp shown in the image, at 50 Hz, the 1.2 μF capacitor has a reactance of 2.653 kΩ. By Ohm's law, the current is limited to
541:
174:
262:
By changing the value of the example in the diagram by a capacitor with a value of 330 nF, a current of approximately 20 mA can be provided, as the
556:
99:
184:
A capacitive power supply usually has a rectifier and filter to generate a direct current from the reduced alternating voltage.
533:
358:{\textstyle X_{C}={\frac {1}{2\pi \;50\,\mathrm {Hz} \;33\cdot 10^{-8}\,\mathrm {F} }}\approx 9.646\,\mathrm {k\Omega } }
593:
214:, connected in series with it protects against voltage spikes during switching operations. An electrolytic capacitor,
66:, which leads to a higher-cost and bulky capacitor. The primary downside of this type of power supply is the lack of
62:, however, a relatively large mains-voltage capacitor is required and its capacitance must increase with the output
442:{\textstyle I\approx {\frac {230\,\mathrm {V} }{9.646\,\mathrm {k\Omega } }}\approx 24\cdot 10^{-3}\,\mathrm {A} }
491:
449:. This way up to 48 white LEDs in series can be powered (for example, 3.1 V/20 mA/20000 mcd).
609:
457:
82:, there will result a gradually-rising voltage at the output, eventually reaching the input (AC) voltage.
263:
196:
37:
521:
242:
can be used as a regulator; the two-terminal device would eliminate R4 and R5 used as a resistive
67:
486:
481:
223:
45:
581:
200:
79:
71:
63:
156:
243:
231:
16:
153:, the current is limited to: 1 amp, per farad, per volt-rms, per radian (of phase). Or
52:
603:
472:
222:
and the peak current (in the range of amps) in switching operations. Above right a
86:
33:
366:
587:
239:
93:
75:
59:
511:
Low cost PSU using a capacitor instead of a transformer (English
Translation)
461:
188:
58:
It is a relatively inexpensive method compared to typical solutions using a
41:
522:
Low cost PSU using a capacitor instead of a transformer (German
Original)
207:
254:
48:
557:"The danger of transformerless power supplies on the connected load"
460:
is needed in any type of protection circuit used for this kind of
253:
146:{\displaystyle I_{c}=C{\frac {\mathrm {d} V}{\mathrm {d} t}}}
534:"The Shocking Truth About Transformerless Power Supplies"
266:
of the 330 nF capacitor at 50 Hz calculates to
582:
Transformerless Power
Supplies: Resistive and Capacitive
226:
can be seen, formed by the current limiting resistor,
375:
272:
159:
102:
441:
357:
238:. If the voltage stability is not too important a
168:
145:
555:Alsayed, Sulaiman Algharbi (November 1, 2021).
85:Capacitive power supplies typically have a low
454:240 V/2653 Ω ≈ 90 mA
258:A lamp that has 48 LEDs - 3 W/230 V
8:
311:
298:
176:amps, per farad, per volt-rms, per hertz.
434:
433:
424:
400:
399:
389:
388:
382:
374:
347:
346:
332:
331:
322:
303:
302:
286:
277:
271:
158:
132:
122:
119:
107:
101:
471:
15:
503:
199:limits the current flowing through the
7:
544:from the original on April 16, 2022.
588:Transformerless Power Supply Design
435:
404:
401:
390:
351:
348:
333:
307:
304:
133:
123:
14:
458:residual-current circuit breaker
20:Basic diagram and sample design
1:
369:, that limits the current to
92:By the equation of state for
78:in the circuit shown should
218:, is used to smooth the DC
626:
187:Such a supply comprises a
594:MKP Metallized Capacitors
476:High voltage warning sign
492:UL (safety organization)
246:in the schematic above.
26:capacitive power supply
477:
443:
359:
259:
170:
147:
21:
475:
444:
360:
257:
171:
169:{\displaystyle 2\pi }
148:
19:
373:
270:
157:
100:
38:capacitive reactance
590:- Designer Circuits
478:
439:
355:
260:
166:
143:
68:galvanic isolation
30:capacitive dropper
22:
561:Electronics World
540:. April 4, 2017.
487:Resistive dropper
482:Electrical injury
409:
338:
224:voltage regulator
141:
44:to reduce higher
617:
569:
568:
552:
546:
545:
530:
524:
519:
513:
508:
455:
448:
446:
445:
440:
438:
432:
431:
410:
408:
407:
394:
393:
383:
364:
362:
361:
356:
354:
339:
337:
336:
330:
329:
310:
287:
282:
281:
230:, and the Zener
201:rectifier bridge
175:
173:
172:
167:
152:
150:
149:
144:
142:
140:
136:
130:
126:
120:
112:
111:
72:double insulated
625:
624:
620:
619:
618:
616:
615:
614:
600:
599:
578:
573:
572:
554:
553:
549:
532:
531:
527:
520:
516:
509:
505:
500:
470:
453:
420:
395:
384:
371:
370:
318:
291:
273:
268:
267:
252:
244:voltage divider
232:shunt regulator
182:
155:
154:
131:
121:
103:
98:
97:
12:
11:
5:
623:
621:
613:
612:
610:Power supplies
602:
601:
598:
597:
591:
585:
577:
576:External links
574:
571:
570:
547:
525:
514:
502:
501:
499:
496:
495:
494:
489:
484:
469:
466:
437:
430:
427:
423:
419:
416:
413:
406:
403:
398:
392:
387:
381:
378:
353:
350:
345:
342:
335:
328:
325:
321:
317:
314:
309:
306:
301:
297:
294:
290:
285:
280:
276:
251:
248:
181:
178:
165:
162:
139:
135:
129:
125:
118:
115:
110:
106:
36:that uses the
13:
10:
9:
6:
4:
3:
2:
622:
611:
608:
607:
605:
595:
592:
589:
586:
583:
580:
579:
575:
566:
562:
558:
551:
548:
543:
539:
535:
529:
526:
523:
518:
515:
512:
507:
504:
497:
493:
490:
488:
485:
483:
480:
479:
474:
467:
465:
463:
459:
450:
428:
425:
421:
417:
414:
411:
396:
385:
379:
376:
368:
365:and applying
343:
340:
326:
323:
319:
315:
312:
299:
295:
292:
288:
283:
278:
274:
265:
256:
249:
247:
245:
241:
237:
233:
229:
225:
221:
217:
213:
209:
205:
202:
198:
194:
190:
185:
179:
177:
163:
160:
137:
127:
116:
113:
108:
104:
95:
90:
88:
83:
81:
77:
73:
69:
65:
61:
56:
54:
50:
47:
43:
39:
35:
32:is a type of
31:
27:
18:
564:
560:
550:
537:
528:
517:
506:
451:
261:
235:
227:
219:
215:
211:
203:
192:
186:
183:
91:
87:power factor
84:
57:
34:power supply
29:
25:
23:
584:- Microchip
240:Zener diode
94:capacitance
76:Zener diode
60:transformer
51:to a lower
498:References
462:LED light
426:−
418:⋅
412:≈
405:Ω
380:≈
367:Ohm's law
352:Ω
341:≈
324:−
316:⋅
296:π
264:reactance
197:reactance
189:capacitor
180:Structure
164:π
80:fail open
55:voltage.
42:capacitor
604:Category
542:Archived
538:Hackaday
468:See also
208:resistor
96:, where
46:AC mains
250:Example
220:voltage
64:current
49:voltage
596:- WIMA
195:whose
397:9.646
344:9.646
40:of a
567:: 1.
206:. A
565:127
386:230
236:IC1
28:or
606::
563:.
559:.
536:.
464:.
422:10
415:24
320:10
313:33
300:50
234:,
228:R3
216:C2
212:R1
210:,
204:D1
193:C1
191:,
89:.
53:DC
24:A
436:A
429:3
402:k
391:V
377:I
349:k
334:F
327:8
308:z
305:H
293:2
289:1
284:=
279:C
275:X
161:2
138:t
134:d
128:V
124:d
117:C
114:=
109:c
105:I
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
