It was my understanding that the circuit will only draw the current thats needed - a 1A servo will only draw 1A.
I have a rather large project so I am using a 24V 5A rated wall adapter, and using buck converters to manage the power. I am testing it with 1 variable buck converter bringing the voltage down to 5V, and this is only powering 1 servo at the moment. The wire connecting the servo to the buck converter was easily able to handle the draw when I was using a 5V 1A adapter with no buck converter, but it burnt up in this new circuit.
For this reason I am curious, does the buck converter set the amp at some higher level? e.g. even though the circuit only needs 1A the buck converter sets the amperage at a fixed value higher?
schrodingers_hat:
It was my understanding that the circuit will only draw the current thats needed - a 1A servo will only draw 1A.
I have a rather large project so I am using a 24V 5A rated wall adapter, and using buck converters to manage the power. I am testing it with 1 variable buck converter bringing the voltage down to 5V, and this is only powering 1 servo at the moment. The wire connecting the servo to the buck converter was easily able to handle the draw when I was using a 5V 1A adapter with no buck converter, but it burnt up in this new circuit.
For this reason I am curious, does the buck converter set the amp at some higher level? e.g. even though the circuit only needs 1A the buck converter sets the amperage at a fixed value higher?
Ohms law says thats impossible. What is possible is that somehow the buck converter became unstable and turned into an oscillator. Some buck converters do not handle inductive and/or capacitive loads very well (motors for example). It can drive the control loop out of its range of stability into oscillation range. This can cause huge voltage spikes which could very much then fry the wiring.
The why on this gets into a topic called Control Loop theory and deals with response times, phase response etc. It's something I am only tangentially familiar with but hope to learn some day.
Thank you for your answer, is there a way to rectify this? EG put a diode leading from the vout of the servo to the vin, like i would in a mosfet circuit or do you have any other suggestions?
schrodingers_hat:
Thank you for your answer, is there a way to rectify this? EG put a diode leading from the vout of the servo to the vin, like i would in a mosfet circuit or do you have any other suggestions?
You can try putting a snubber on the output (a resistor and capacitor in series to ground). Without a scope or something to confirm oscillation and to get the frequency you would just be guessing at the values.
It was my understanding that the circuit will only draw the current thats needed - a 1A servo will only draw 1A.
That is correct, and the servo should only draw the full 1A under load (or when stalled) or when moving at full speed. And sometimes motors draw more than their rated current at start-up, but I'm not sure if that's the case with servos.
What's the current rating on the buck converter? In general, you should give yourself some safety margin... Using a buck converter rated at 1 Amp is like lifting 100 pounds of bricks with a rope rated for 100 pounds... It will probably work, but I wouldn't stand underneath the bricks... Especially if I bought the cheapest rope I could find on eBay. 
am using a 24V 5A rated wall adapter,
Switching regulators are nearly 100% efficient. That means with 24V in and 5V / 1A out, the 24V supply only needs to supply a little more than 0.2 Amps.
Servos and other DC motors draw current that depends on the load, so the designation of "1 amp servo" is very misleading. You must plan on being able to supply the stall current rating of the servo you are using, which should be available from the manufacturer. Note that upon startup, DC motors briefly draw the stall current, and can draw TWICE that amount if the direction of rotation is suddenly reversed.
Then, check whether the buck converter can handle this amount of current. Finally, did you verify that the (variable) buck converter was set to 5V when a reasonable load is connected?