JW
Well-known member
Okay, back again. Pulsing is persisting, even after making sure 1K is the first resistor (like the most recent schematic in PRR's last post. ) My cap value is 1uF. How low can I go with capacitance?
The problem with Neon..
- Thread starter Dr nEon
- Start date
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JW
Well-known member
abbey road d enfer said:
Sorry to bump this one again. Can the cap be lower than 1uF? Suggestion earlier was to lower cap value to treat the pulsing problem. I'm already at 1uF
It should not be pulsing.
1- what is the frequency or repetition rate of pulsing?
2- is you capacitor high enough voltage? (Abbey suggested 250V. Non polars will be larger.)
3- are resistor values accurate and as drawn?
Pulsing (oscillation) could be caused by one of several factors. Neon lamps will have a break down voltage above which they begin conducting so a weakly charged reservoir cap could cyclically charge and discharge.
Likewise an under voltage capacitor could break down, but usually that does not repeat (one and done).
BTW be careful messing with mains voltage, people can and do die from careless handling.
JR
1- what is the frequency or repetition rate of pulsing?
2- is you capacitor high enough voltage? (Abbey suggested 250V. Non polars will be larger.)
3- are resistor values accurate and as drawn?
Pulsing (oscillation) could be caused by one of several factors. Neon lamps will have a break down voltage above which they begin conducting so a weakly charged reservoir cap could cyclically charge and discharge.
Likewise an under voltage capacitor could break down, but usually that does not repeat (one and done).
BTW be careful messing with mains voltage, people can and do die from careless handling.
JR
Just try it. The worst that can happen is the capacitor voltage falls below the neon extinguishing voltage so it turns on and off at 60Hz, basically the same problem as when powered by AC.JW said:
I've seen neon bulbs on AC flicker and such, so maybe (and presuming your circuit is as shown) the neon bulb is just faulty/worn out/doing strange things. According to the links below, this could indicate it being near end-of-life.
Is there something about neon that you really want to use it? Probably the neon bulb is integrated into an on-off switch, as in one of the photos on Wikipedia.
Why not use a orange, green or blue LED? This can be powered through a resistor from a unit's low-voltage power supply, and be much lower voltage and have no noise.
Here's probably more than you want to know about neon bulbs:
https://www.intl-lighttech.com/specialty-light-sources/neon-lamps
https://en.wikipedia.org/wiki/Neon_lamp
JW
Well-known member
Thanks guys.
I checked one more time that the cap was rated at 250V (yes!) and circuit was exactly the same as the last PRR post on page 2.
I'm using 1N4003 diode. The reason I want to use these lights is I already have them installed in numerous pieces of gear. I just thought it was SO convenient to run a nice bright cool looking light right off the mains. No worrying about dropping resistors. But then I read this thread. . . . .
Anyway, I tried rectification for a second piece of gear's neon (exactly the same as the circuit) and beating is still there. I don't think it's the bulbs themselves.
I checked one more time that the cap was rated at 250V (yes!) and circuit was exactly the same as the last PRR post on page 2.
I'm using 1N4003 diode. The reason I want to use these lights is I already have them installed in numerous pieces of gear. I just thought it was SO convenient to run a nice bright cool looking light right off the mains. No worrying about dropping resistors. But then I read this thread. . . . .
Anyway, I tried rectification for a second piece of gear's neon (exactly the same as the circuit) and beating is still there. I don't think it's the bulbs themselves.
