Low Current High Voltage Plasma Speaker - Page 1
Forum section: electronics / projects

author: megahz
author_rank: Regular Contributor
timestamp: June 22, 2013, 11:30:42 pm
content: So I have been wanting to make a plasma speaker for a while, but I don't know if I should, because I get pretty nervous around high current, is there a way I can make a low current plasma speaker, that possibly wont kill me if I do accidentally get shocked? (I'm not intentionally going to touch it, bu I am a bit clumsy)

author: Unknown
author_rank: Unknown
timestamp: June 23, 2013, 06:21:17 am
content: I would say start with a low current supply and then step it way up in voltage. Don't use a MOT, but maybe a small flyback would be OK. My understanding is that it's the voltage that matters, not the current.I would also say if you're not comfortable enough/careful enough around high voltage to think you won't accidentally touch it, may not be the best idea to build it.

author: Neilm
author_rank: Super Contributor
timestamp: June 23, 2013, 12:20:33 pm
content: Quote from: duskglow on June 23, 2013, 06:21:17 amWrong.What kills you is the current passing through the heart - all that is required is a few milliamps. The high voltage that is present will allow this current to flow. The actual safe levels depend on conditions, for example how wet it is.To put this is perspective, if you get a static shock and you hear it the voltage was probably in the order of 8kV or more. It hurts as there is some current flow but as it is not very much and not enough to kill you.As important is the path the current takes. If it goes across the chest (through the heart) the chances of survival are less than if it does down the body. One tip when using High Voltage is to keep one hand in a pocket as it reduces the chances of current passing across the chest.On the flip side, there is a urban myth that a technician wanted to know what the resistance of the human body is. Knowing that the skin is a barrier to electricity he got some sharp points and connected them onto a multimeter. He then pushed the probes through his skin. The current from the meter killed him. (I don't know if it is true or not but it shows the point)Quote from: duskglow on June 23, 2013, 06:21:17 amAgreedNeil

author: Unknown
author_rank: Unknown
timestamp: June 23, 2013, 02:46:12 pm
content: I should have been clearer - when I said "voltage that matters", I meant in terms of creating the plasma, not in terms of danger.

author: penfold
author_rank: Frequent Contributor
timestamp: June 23, 2013, 06:20:15 pm
content: Try thinking what you can do to avoid touching it.(just as a side note, whilst it is the voltage that matters in terms of striking the arc, you will need a current above a threshold that is sufficient to maintain the plasma, I've no idea what that is though!)The majority of the electronics will be on the low voltage side so perhaps some kind of earthed metallic shield to prevent you accidentally touching any of the high voltage side would be a start. There's no fool proof method when working with dangerous electronics so you just have to work out what you feel comfortable with and how you think you can protect yourself and then get somebody else (someone knowledgeable) to check that you've not over looked any risks.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 23, 2013, 07:19:13 pm
content: Use a high frequency AC flyback. High frequency AC is safer than DC or low frequency AC (but still be careful) and the DC path to ground means that capacitance cannot store a charge after you turn it off.

author: dannybeckett
author_rank: Contributor
timestamp: June 24, 2013, 01:31:27 pm
content: Quote from: Neilm on June 23, 2013, 12:20:33 pmIronic how your post starts out with a very arrogant 'Wrong.', yet you're spreading urban myths around. Just to clarify - the man who pushed the multimeter probes into his skin most certainly did not die of electrocution.

author: Neilm
author_rank: Super Contributor
timestamp: June 24, 2013, 05:40:21 pm
content: Quote from: dannybeckett on June 24, 2013, 01:31:27 pmI did say the the man killing himself with a multimeter was an urban myth.As for the rest of it, IEC61010 (the test equipment safety standard) defines hazardous voltages in terms of both voltage and current until you reach a voltage of about 15kV, in which case it defines it in terms of stored charge for both normal and single fault conditions. If you read the standard it is in section 6 (6.4 I think). Figure 2 in the standard gives the maximum permissible levels on a graph.Neil