18v To 9v ?

[JimInMO]

Hello, first post. Hope this is the correct forum. I have an unused 18v Dunlop power supply and need a 9 volt supply for a Digitech Bad Monkey pedal. Any simple way to convert the Dunlop to 9v? Add a resistor in line ?? I'm pretty challenged electronically but can handle a soldering iron and follow directions.

[Paul Marossy]

You could use a simple two-resistor voltage divider to halve the voltage. But you also have to look at the current involved. If you have a 18V 500mA power supply and you want to power a 9V 50mA pedal, you will be getting significantly higher voltage because your wall wart has hardly any load on it in comparison to the current is was designed to deliver.

[JimInMO]

You could use a simple two-resistor voltage divider to halve the voltage. But you also have to look at the current involved. If you have a 18V 500mA power supply and you want to power a 9V 50mA pedal, you will be getting significantly higher voltage because your wall wart has hardly any load on it in comparison to the current is was designed to deliver.

Hmmmm, forgot the amperage part. The PS delivers 18v 150ma and the Monkey requires 9v 300ma. Oh well, power supply's are relative cheap compared to batteries. How is the two-resistor divider made? Is this a pre-made device or something that can be assembled by an amateur?

[Ripthorn]

With the voltage divider, you should also take into account the load resistance. As soon as a voltage divider has a load, the simple equation for dividing the voltage changes a little. I designed a power conversion circuit and trying a simple resistor based circuit didn't work. You could use a voltage regulator, it is a chip that takes an input voltage and gives a certain output voltage. They are pretty cheap (usually less than a dollar for your run of the mill kind) and available at mouser, digikey and maybe even radioshack, though I am not positive on that.

[Paul Marossy]

You could use a simple two-resistor voltage divider to halve the voltage. But you also have to look at the current involved. If you have a 18V 500mA power supply and you want to power a 9V 50mA pedal, you will be getting significantly higher voltage because your wall wart has hardly any load on it in comparison to the current is was designed to deliver.

Hmmmm, forgot the amperage part. The PS delivers 18v 150ma and the Monkey requires 9v 300ma. Oh well, power supply's are relative cheap compared to batteries. How is the two-resistor divider made? Is this a pre-made device or something that can be assembled by an amateur?

It might actually work, you'll probably get a little less than 9V when the Monkey is connected to it, but it might be enough for it to still function properly.

See this page for voltage divider: http://hyperphysics.phy-astr.gsu.edu/hbase...ric/voldiv.html

[JimInMO]

You could use a simple two-resistor voltage divider to halve the voltage. But you also have to look at the current involved. If you have a 18V 500mA power supply and you want to power a 9V 50mA pedal, you will be getting significantly higher voltage because your wall wart has hardly any load on it in comparison to the current is was designed to deliver.

Hmmmm, forgot the amperage part. The PS delivers 18v 150ma and the Monkey requires 9v 300ma. Oh well, power supply's are relative cheap compared to batteries. How is the two-resistor divider made? Is this a pre-made device or something that can be assembled by an amateur?

It might actually work, you'll probably get a little less than 9V when the Monkey is connected to it, but it might be enough for it to still function properly.

See this page for voltage divider: http://hyperphysics.phy-astr.gsu.edu/hbase...ric/voldiv.html

Ok, Thanks all, I think I can figure out the schematic. I have some variable resistors around here somewhere. Guess I can play with them to find the correct values then replace with fixed resistors.

Thanks again,

Jim