What is it?
When I’m working on small projects, I like to power them off of a power-bank or a similar item. Sometimes, the device draws such a small amount of power that it shuts down the power to the USB port as it thinks the device is off.
What does it do?
This device that I’ve designed will stay on by pulsing the power line to ensure that it doesn’t shutdown. It utilizes the 555 timer in an Astable circuit. With the configured resistors and capacitor there is a 50% duty cycle which equates in roughly a 10mA draw with a pulse of approx 130mA. Combined with the draw of the device, this shall be enough to keep the powerbank active. The data lines are directly connected and unaffected.
What is in the kit?
- Male USB Type A Header
- Female USB Type A Header
- 2 x Capacitors
- 3 x Resistors
- 555 chip
If you wish to modify the output for a different duty cycle, the timing can be calculated using the following website:
This is provided as a kit with the stock resistor values. If you wish to purchase a case or an assembled unit please select the appropriate option.
I have designed a 3d printed case which has been designed to be screwless and snaps together with a snug fit.
Thingiverse Case Download
All components are through hole so it’s suitable from novice upwards
Stock and different options
If you are looking to buy more that I have listed, or if one particular option that you are looking for is out of stock, please contact me and I should be able to arrange listing it for you!
The pass through should work with all devices as the data lines are unaffected. With the resistor values chosen on it’s own it should not keep most powerbanks alive but combined with a very low power device it should be enough to stop the powerbank from powering off. Since the resistors are easily changed it can be modified to meet your needs