Can a 1n4009 protect a LED from reverse breakdown voltage when powered by mains?

  • Thread starter Thread starter thankz
  • Start date Start date
  • Tags Tags
    Reverse Voltage
AI Thread Summary
Using a 1N4009 diode to protect an LED from reverse breakdown voltage when powered by mains is not sufficient without additional components. The discussion highlights the importance of including a bridge rectifier and capacitor for proper current and voltage regulation, especially with 120V AC mains. Concerns about safety and the user's understanding of high-voltage circuits are raised, emphasizing the need for caution and proper circuit design. The user expresses confidence in their ability to handle mains voltage but is advised to reconsider their approach for reliability and safety. Overall, the conversation stresses the necessity of a well-designed circuit when working with potentially lethal voltages.
thankz
Messages
265
Reaction score
40
I want to power a led off mains, here's my thinking on it:

resistor-->led-->1n4009 to protect against reverse breakdown voltage, is there anything I'm missing and will it be reliable?
 
Engineering news on Phys.org
Im a bit unsure if I should be giving you circuit advice for mains powered projects
as I don't really know if you have the experience dealing with potentially lethal voltages

The way you described above isn't correct
You also haven't stated what mains voltage you have at your location or what type of LEDs you want to use

This gives me even less confidence in your knowledge level

The circuit I will give and strongly advise you follow and with skilled supervision is this one ...

220V-leds.jpg
Dave
 
it's just 120 v ac, I don't see why I need a bridge rectifier and cap when all I want to is current and voltage limit a 1.2v led and use a 1n4009 to protect the led against reverse piv? maybe I'm not using the right terminology but I'm comfortable working around mains, I'm pretty sure I won't die. would you have questioned me if I had used a neon bulb and a resistor? basicly it's a half wave rectifier and I'm just adding a voltage drop and current limiting. if I used a varic and fast blo fuse, high wattage resistor I would test this out myself before asking, just wondering.
 
Last edited:

Thread 'Underwater piezoelectric sensor array receive sensitivity'

Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
View full post »

Thread 'Following up on the recent thread about Earth Resistance measurements'

I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
View full post »

Thread 'Question about bonding ground and neutral'

I am not an electrical engineering student, but a lowly apprentice electrician. I learn both on the job and also take classes for my apprenticeship. I recently wired my first transformer and I understand that the neutral and ground are bonded together in the transformer or in the service. What I don't understand is, if the neutral is a current carrying conductor, which is then bonded to the ground conductor, why does current only flow back to its source and not on the ground path...
View full post »

Similar threads

Can RGB LED simulate incandescent bulb 'glow'?
Replies
3
Views
3K
Deciding batteries for my circuit
Replies
3
Views
1K
Charlieplexing: LEDs have different brightness
Replies
14
Views
2K
Calculating Values for PN2222A LED Circuit
Replies
5
Views
3K
Buck converter will power LED's but voltage divider will not....
Replies
4
Views
2K
How is the MOC 3052 triac driver optocoupler supposed to work?
Replies
4
Views
2K
Mosfet SSR, flyback shunt/crowbar safety circuit
Replies
1
Views
2K
Calculating the Efficiency, total output power and irradiance of LEDs
Replies
2
Views
1K
Bypassing a joule thief until voltage gets low enough
Replies
2
Views
2K
Powering a 3W LED circuit or driver?
Replies
14
Views
3K

Hot Threads

Recent Insights

Back
Top