Andy Roid
My Antonn project is having a power problem which I hope someone can help me with. I am supplying the controls with 12vdc and 5vdc from an old computer power supply. (The 5vdc runs the Io Tiny and servos which works fine.)( 12vdc runs a remote controller board.) I have two more power requirements. I require 7.2 vdc and 3.8 - 4.0 vdc power. The 7.2 vdc supplies a Scary Terry Audio Board and the current shouldn't exceed about 500 ma. The other device uses 3.8 to 4.0 vdc at about 150ma. There was no data on the smaller device, so I need to guess. (origionally ran off of a LiPo battery.)
I purchased a DC to DC converter able to supply the correct voltages and currents from the 12vdc and 5vdc supply I have available. I wired up the converters, set the proper voltages, but the converter fails to work with either device. I assume the converter supplies a type of PWM DC power. The units seem unable to tolerate the pulsing.
I have a limited electronic knowledge. I need to figure out how to build two regulated supplies, one able to supply 7.2 vdc from 12 vdc and the other 4 vdc from a 5 volt supply. Can anyone help?
WOW,,, Now I am in trouble. I was told to try the talk servo which if it works may eliminate using this board altogether. I still have the need for 12vdc to 7.2 to 8 vdc on another project so your help will not be wasted. I will be ordering a couple of LM 7808 s soon no mater if the talk servo works or not.
Thanks for the help and info. (The cap data is really helpful.)
In line switching regulators are available for servos. So you can drop from your feed power to 7.2 volts, 6 volts or 5 volts. Just whatever your servo needs. You can make them yourself too. Switching are way better than linear because you do not waste all the voltage difference as heat.
http://www.ebay.com/itm/Lot-of-5-Buck-Converter-US-Seller-4-75-23V-In-1-17V-Out-Step-Down-Mini-360-/272604581988?hash=item3f787fd064:g:WZsAAOSwjwlXBAlD
these handle servos well and you can glue on a 10mm x 10mm heatsink if you are constantly pushing it to 2 amps or more.
I don't know why the buck converters I have don't work? I want to try the LM 7808 s next.
@ptp and @jstarne1,
Just for future knowledge, how clean is the output of the buck converters?
Can I add filtering, or should there be enough on the converter?
Since they are for power you shouldn't need any filtering. Switching regulators are pretty efficient, usually over 90 percent. However results may vary depending on your supplier.
My application is to power an audio board. That is why I was curious about more filtering.
as long as your are only powering the board you are fine, switching regulators use between 25000 and 40000 hertz, which is likely outside the audible range a amplifier would pick up