Power Supply Question and Request.

Hi Al,

What you describe is possible, but to build a universal supply will not be as efficient as building to a specification. For a specific application one would need to know the voltage of the source of power. The amount of current that the source can deliver would be a limiting factor on the outputs. For example the voltage of your source times the limit of its current will define the wattage of the source. The voltages of your secondary systems times each of their respective currents are the power in watts that is being consumed by your device. The power consumed can't be greater than the power available at the source. You would need to know the different voltages that are needed as well as the current that will be needed for each voltage. There is a big difference between building a 5 volt one amp supply and a 5 volt 10 amp supply. I am not an engineer and so I have found for my own projects that there are a lot of DC to DC converters commercially available at reasonable prices that I integrate into my designs. Most of these converters use switch mode power supply (SMPS) designs and are very efficient. (Some in excess of 90%). this is very important particularly if your device is running from a limited supply such as a battery. Many of these converter modules will take a range of voltages for input and deliver a range of voltages for output. In this way I can input from 4 V to 36 V and get 1.2V to 34 V out. These are called BUCk converters as they reduce the voltage. Here is an example of a BUCK converter:

http://www.ebay.com/itm/DC-DC-CC-CV-Buck-Converter-Step-down-7-40V-to-0-8-35V-12A-Power-Supply-Module-/272614244686?hash=item3f7913414e:g:p7QAAOSwuLZY39YW

You can see where a series of these converters could be tied into a voltage source and each be tuned to a specific output voltage. As long as your device doesn't try to draw more current than the device is capable of they seem to work very well. Of course for the money they are great for non-critical applications. I would not recommend them for any critical or medical application.

Rather than continue to ramble I will send the conversation back to you and we can expand the discussion if this is what you are interested in.

I call my approach to design the Borg approach as I do not design new technology by rather assimilate the designs of others.

John

Hi Al,

What you describe is possible, but to build a universal supply will not be as efficient as building to a specification. For a specific application one would need to know the voltage of the source of power. The amount of current that the source can deliver would be a limiting factor on the outputs. For example the voltage of your source times the limit of its current will define the wattage of the source. The voltages of your secondary systems times each of their respective currents are the power in watts that is being consumed by your device. The power consumed can't be greater than the power available at the source. You would need to know the different voltages that are needed as well as the current that will be needed for each voltage. There is a big difference between building a 5 volt one amp supply and a 5 volt 10 amp supply. I am not an engineer and so I have found for my own projects that there are a lot of DC to DC converters commercially available at reasonable prices that I integrate into my designs. Most of these converters use switch mode power supply (SMPS) designs and are very efficient. (Some in excess of 90%). this is very important particularly if your device is running from a limited supply such as a battery. Many of these converter modules will take a range of voltages for input and deliver a range of voltages for output. In this way I can input from 4 V to 36 V and get 1.2V to 34 V out. These are called BUCk converters as they reduce the voltage. Here is an example of a BUCK converter:

http://www.ebay.com/itm/DC-DC-CC-CV-Buck-Converter-Step-down-7-40V-to-0-8-35V-12A-Power-Supply-Module-/272614244686?hash=item3f7913414e:g:p7QAAOSwuLZY39YW

You can see where a series of these converters could be tied into a voltage source and each be tuned to a specific output voltage. As long as your device doesn't try to draw more current than the device is capable of they seem to work very well. Of course for the money they are great for non-critical applications. I would not recommend them for any critical or medical application.

Rather than continue to ramble I will send the conversation back to you and we can expand the discussion if this is what you are interested in.

I call my approach to design the Borg approach as I do not design new technology by rather assimilate the designs of others.

John

Hi John

Thanks for your reply.. i have tried of the shelf solutions and YES they work but it isnt what we are after.

What im after is a schematic so we can incorporate it in to a board we are having built for robotics control..

What we are after is something with a common input rail and then an output rail with selectable voltages - preferably selected by a switch or jumper..

If anyone can provide a converter schematic and maybe an explanation of what components need to be changed for each voltage output level that would be ideal....

Hi Al,

OK I understand better now. How much current will each of the taps draw? It is important to properly size unless weight isn't a problem for your application. Still, even if weight isn't a problem it is a shame to have 10 amps available and all the heavy duty hardware to support it when all you need is 100 mA.

John

Hi John

\The most current required is 3 amps - but mostly 2 amps is sufficient -- weight is kind of an issue but not necessarily a problem...