First of all, please DO NOT attempt to open any power supply and tweak what's inside unless you know what you're doing and/or are a professional. With that said, this circuitry video will teach you how to crack open a wall transformer power supply without destroying the transformer.
You can use this process to power a circuit with a power pack. Remember to be safe and turn off the power when you start.
Save 20% on everything in the Gadget Hacks shop this Cyber Monday with coupon code CMSAVE20. Apps and software in the store have even bigger savings with code CMSAVE40. And for the largest discounts, check out the online courses for 70% off with CMSAVE70. Don’t know what to get? We can help: