Just an idle thought, I saw just about to out date 9V batteries for $0.08 @ on the web. They stack nicely end to end and I have done it for things like 40-60V and since there is no current consumption it would probably go years past the posted outdate.
Price is right.
500V is about 56 of them.
1500V is more.
how much does your ESL need?
How much volume does 56/500V of these guys take up?
500V is about 56 of them.
1500V is more.
how much does your ESL need?
How much volume does 56/500V of these guys take up?
You have to be careful because the short circuit current is probably large enough to kill you, otherwise I don't see any major drawbacks.
Thanks guys no active projects right now, I still have a roll of mylar and graphite powder from 35yr. ago (you know how it is). Just thinking out loud.
True, but then again, you have to be careful anyway because no matter what supply you use for the diaphragm, the voltages on the stators can kill you when there is signal present.
It would be poor design to create a murderous speaker.
Ordinarily, the bias leakage/resistance of the cells should be monumentally high. Therefore, you can always have a series resistor inside the bias supply box sufficiently large to limit the current emanating from the box to non-lethal power.
But for a direct drive ESL, buy life insurance before building.
Ben
I wrote about the stators. You can (and should) indeed limit the current of the diaphragm supply to non-lethal values, but the transformer or amplifier driving the stators can always supply a potentially lethal current when there is a loud signal present. The only thing you can do about that, is to ensure that no-one comes near the stators when there is music playing.
I've given it some more thought and I think that the safest way to make a diaphragm supply with 9 V batteries is to give each group of (at most) five batteries its own 1 Mohm (or so) series resistor. You then get a huge chain of battery-battery-battery-battery-battery-1 Mohm-battery-battery-battery-battery-battery-1 Mohm-battery-battery-battery-battery-battery-1 Mohm and so on.
When you unintendedly complete the circuit through your body, there are two cases to consider:
-Imagine you touch the most positive and most negative poles of a group of five 9 V-batteries. In that case, there will be 45 V across your body, which is still a safe value as long as you don't do anything unusual (such as putting medical electrode fluid on your skin before working on your electrostats).
-Imagine there are several groups of five batteries involved in the circuit that is completed by your body. The worst case current is then only 90 uA: two groups of 45 V with one resistor in between them and the skin resistance (which I neglect here). 90 uA is quite safe.
The voltage across each 1 Mohm resistor also stays limited to 90 V or less, which is well below the maximum voltage specification of a typical 1/4 W through-hole resistor.
When you unintendedly complete the circuit through your body, there are two cases to consider:
-Imagine you touch the most positive and most negative poles of a group of five 9 V-batteries. In that case, there will be 45 V across your body, which is still a safe value as long as you don't do anything unusual (such as putting medical electrode fluid on your skin before working on your electrostats).
-Imagine there are several groups of five batteries involved in the circuit that is completed by your body. The worst case current is then only 90 uA: two groups of 45 V with one resistor in between them and the skin resistance (which I neglect here). 90 uA is quite safe.
The voltage across each 1 Mohm resistor also stays limited to 90 V or less, which is well below the maximum voltage specification of a typical 1/4 W through-hole resistor.
I used to simply unplug my supply from the wall for an easy four or more hours of mains free listening then plug the supplies back in before going to bed. good thought tho, use care for those who decide to try it out, probably not a plan for people with kids.
- Status
- Not open for further replies.