Weird voltages with GPIO

[themagicat]

When I plug a resistor into the 3V3 pin and the GND pin and measure the voltage I get 3.3V, as expected. But when I use GPIO with 3V3 pins and the same resistor I only measure 0.75V. Why is this? What can I do to fix it? I need the 3.3V for a solid state relay. Thanks.

[dhylands]

How exactly is the resistor connected up in relation to the SSR? Which SSR are you using? What value of resistor are you using?

What's probably happening is that the resistance of your resistor and the resistance of the SSR are making a resistor divider and that's where your voltage is coming from.

[themagicat]

The problem is that GPIO is 12.6 mA while 38.5 mA. Is there a way to get more amperage there? My relay requires 98mW to switch

[torwag]

Most likely, you try to draw to much current from the GPIO. There is no way to increase it. What you need to do is to uses a small transistor like a FET and use this to trigger the SSR.