Doepfer

Enter your vote today!  A new poll has been created for the 
Doepfer_a100 group:

Would you want Doepfer to manufacture the A164 Manual Gate module (second version)? (www.doepfer.de/a164)  

  o Yes! 
  o maybe... 
  o no. 


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Thanks!

Hello,

I have a technical question about safety in doepfer use, i¹m preparing an
electro-acoustic performance to be presented around  a fountain, the idea is
to use the fountain¹s water as a sort of multiple, i mean i would build a
box to carefully sepparate the jack¹s GND and +V, then would connect all +V
to the water keeping the GND in one of my hands, this way the water would be
a conducteur and my body the resistor or the attenuator for the voltage, i
would then join GND and +V and use it as a CV source...

I was testing with a 9v battery in my bathtub and could have total voltage
attenuation control - 0v to 9v

Would i be in risk here, with the doepfer connected to an ac supply?
Any major not advised thing would be envolved here?

To make it safer could i isolate through optocouplers the water line and the
doepfer line, would this resolve any problem?
Any help, ideas?

Thanks in advance

Best regards
andre



[Non-text portions of this message have been removed]

> Hello,
>
> I have a technical question about safety in doepfer use, i¹m preparing an
> electro-acoustic performance to be presented around a fountain,
> the idea is
> to use the fountain¹s water as a sort of multiple, i mean i would build a
> box to carefully sepparate the jack¹s GND and +V, then would
> connect all +V
> to the water keeping the GND in one of my hands, this way the
> water would be
> a conducteur and my body the resistor or the attenuator for the voltage, i
> would then join GND and +V and use it as a CV source...
>
> I was testing with a 9v battery in my bathtub and could have total voltage
> attenuation control - 0v to 9v
>
> Would i be in risk here, with the doepfer connected to an ac supply?
> Any major not advised thing would be envolved here?
>
> To make it safer could i isolate through optocouplers the water
> line and the
> doepfer line, would this resolve any problem?
> Any help, ideas?
>
> Thanks in advance
>
> Best regards
> andre

I'd be very cautious with water and equipment that is connected to mains
voltage. You have to make 100% sure that any contact between water and the
A-100 power supply is impossible (mains and +/-12V).

From my point of view this would be a safe solution: Use a very long patch
cable to establish the connection between your "wet installation". The minus
terminal of the external 9V battery is connected to the GND of the cable,
the tip of the cable is used for the control voltage generated by your body
and the water. The length of the cable has to make 100% that no humidity or
water could reach the A-100 frame.

Another solution would be the usage of batteries for the A-100 power supply.
Then there is no connection between the A-100 and mains (e.g. two 12V
rechargeable batteries for +12V and -12V).

In any case you have to be very careful and I'd dissuade to realize the
project if you are not sure if you can keep all safety conditions.

Best wishes
Dieter Doepfer

Hi Andre

> Would i be in risk here, with the doepfer connected to an ac supply?
> Any major not advised thing would be envolved here?


There are two major risks of water and electricity:

It is NOT the water in the basin itself, but the connection it can make 
to earth. The danger of the water in the bathtube is not the water in 
the bathtube, but the electrical connection to ground which is provided 
by the water, that is running through the drain to the ground.

THe other and more important aspect of danger of water with any kind of 
electronics is, that you will have wet hands and water is dripping 
around from your hands into the housing and will find its way to the 
powersupply. Then it will find a possibility to shorten 220 Volts from 
the next corner powerplant direct to the 12V driven modules. And I 
assume you worked hard for the money to buy them.


So my decent hint is: Remove the AC-Powersupply from the housing and 
install a connector (E.g. asymetric XLR) for +12V, -12V, and Ground.

Now you can feed this with any kind of DC-power. Either you build the 
original Doepfer powersupply in a separate waterproof housing, or you 
use some batteries or accumulators for it.

I once modified a a 3HE Housing for the usage as portable theremin. It 
uses 12 V Accumulators:

http://fa.utfs.org/diy/a100/index.html

You may have to scroll down the left frame to find the pics with the 
accumulators


Florian

Hello,
Thankx for the sugestions!

can you give me any internet link where i could maybe buy those 
accumulators?
do they have a separate charger?
i have two portable cabinets, how long does the batteries would last?

best regards
andre

On May 21, 2007, at 2:08 PM, Florian Anwander wrote:

> Hi Andre
>
>  > Would i be in risk here, with the doepfer connected to an ac supply?
>  > Any major not advised thing would be envolved here?
>
>  There are two major risks of water and electricity:
>
>  It is NOT the water in the basin itself, but the connection it can 
> make
>  to earth. The danger of the water in the bathtube is not the water in
>  the bathtube, but the electrical connection to ground which is 
> provided
>  by the water, that is running through the drain to the ground.
>
>  THe other and more important aspect of danger of water with any kind 
> of
>  electronics is, that you will have wet hands and water is dripping
>  around from your hands into the housing and will find its way to the
>  powersupply. Then it will find a possibility to shorten 220 Volts from
>  the next corner powerplant direct to the 12V driven modules. And I
>  assume you worked hard for the money to buy them.
>
>  So my decent hint is: Remove the AC-Powersupply from the housing and
>  install a connector (E.g. asymetric XLR) for +12V, -12V, and Ground.
>
>  Now you can feed this with any kind of DC-power. Either you build the
>  original Doepfer powersupply in a separate waterproof housing, or you
>  use some batteries or accumulators for it.
>
>  I once modified a a 3HE Housing for the usage as portable theremin. It
>  uses 12 V Accumulators:
>
> http://fa.utfs.org/diy/a100/index.html
>
>  You may have to scroll down the left frame to find the pics with the
>  accumulators
>
>  Florian
>
>

Hi Andre

> can you give me any internet link where i could maybe buy those 
> accumulators?
I bought them at a local shop. The internet site is: 
www.conrad-electronics.de

I do not know the exact naming.


> do they have a separate charger?
They are standard accumulators, which can be used with standard 
chargers; but since I never had a accumulators before, I had to buy a 
new charger.

> i have two portable cabinets, how long does the batteries would last?
I don't know. Mine single row cabinet lasts for around 4 hours or longer.

Which one you have to use is quite simple: check the amount of ampere 
youre modules are drawing, think about how many hours they should run 
without a break, this gives the value for the capacity which is given in 
mA/h



If you use two accumulators for starting a car they will last long 
enough for longer installations.

Florian

Uuuups

> Which one you have to use is quite simple: check the amount of ampere 
> youre modules are drawing, think about how many hours they should run 
> without a break, this gives the value for the capacity which is given in 
> mA/h
I should correct this: You should use some capacity which is around 20 
to 30 percent higher.

Also one remark: I used the accumulators directly at the DC connection 
to the modules. So the voltage is not regulated and the tracking of the 
VCOs (and similar parameters) will be not V/Octave !

Florian