shadowcentaur

@attila Darn, I thought the 250mA was for the audio jack. Looks like I'll need to get a power opamp for their kits then. Thanks for confirming.

I'm trying to develop some labs for my students where the higher AC output current of the audio jack would really come in handy. I've got the AD2 plugged into a barrel jack to the wall. I've got an audio cable in the AD2 headphone jack, with the other end in a jack-to-breadboard adapter, then on the breadboard i've got a 2.8 ohm DC resistance loudspeaker. Waveform generator is set for 2kHz, 250mV peak, but measuring the voltage across the speaker is giving me much less than 250mV. DC resistance of the cable with adapter is under an ohm on my multimeter. The speaker is very quiet, much quieter than when connecting directly to the wavefom generator W1 and ground. The maximum output current in the specs is 250mA, so 250mV/2.8ohm=89mA is less than spec, but I'm just not getting even close to that. I'm seeing R165 in the audio jack schematic as a series 33 ohm PRG18BB330 thermistor, but then if output impedance is 33 ohms, how on earth would it ever output the stated 250mA? This little guy has a trip current of 70mA according to the datasheet, and 5V/33 ohm=150mA, both of which are giving me substantially less than the 250mA current I was looking for. I'm hoping to use the high AC currents for some fun magnetic experiments, but can't seem to get the audio jack to deliver any significant current. I don't even need a real load, I just want the high current for some current sense transformer experiments. I was hoping to avoid needing to use a step-down transformer or any other additional steps that will lead to student mistakes. Anyone know what I'm messing up here?