As far as I understand, diode bridges are mainly used to convert AC into DC, but one can also use them just to ensure an expected DC output polarity for arbitrary DC input polarity. I have some small energy devices (3V-5V, <1A) that require an expected polarity and I want to safely connect them to a power source that is likely to be used with different polarity. How do I find the right type of diode bridge and what disadvantages exist when using it? Given a safe span of input current, does the diode bridge just act like a simple resistor? If so, how high is its virtual resistance, so how much energy would I loose compared to ensuring right polarity by other means?
The main problem with a diode bridge is the fact that you always have two diodes in series with your circuit, and this creates a voltage drop of about 1.4 V between the power source and the load.
The power loss is simply this voltage drop multiplied by the load current.
It also means that you cannot connect the negative side of the load, which you might ordinarily consider to be "ground", to any external ground, which might be connected to either side of the power source.