SPDT Relay with delay using transistors How to

Get a 5v relay and then rig up a simple RC timer and transistor to switch it.

PDT relay and small 2-3 second timer would do the job. I don't know where t o get such a relay or timer, but using transistors and possibly a 555 seems like a more reasonable solution.

itch no more.

idance in making a solution for this problem.

utomate.

ses this port for charging as well as USB OTG to connect USB peripherals. T he problem is it won't usually charge while in OTG mode. Just applying 5v t o the power lines of the USB port won't make it charge.. To get it to charg e, you have to short the data+/- lines together. Then as long as you keep p ower applied to the Power +/- lines it will continue to charge without shor ting the data +/-. You can then connect usb devices to the data lines and t he PC and they work.

t to be on an automatic timer.

ces at the same time. As it is now, I have to plug the usb hub in with the SPDT switch in shorted position and then flip the switch every time I conne ct the hub. I want to make it all automatic. It needs to have the lines sho rted for a few seconds and then switch in the lines for the USB hub.

nd pin as a switch.. i.e. leave the ground wire disconnected in the USB cab le. The shield wire is used to carry ground. When you plug it into the tabl et pc it connects the shield to the GND wire (since they are tied together on the tablet's USB port) and completes the circuit.

That would work, but I have a bunch of transistors caps and resistors that I would like to learn how to put to use. I am just starting out in building electronics.

I get the feeling that just a transistor or two and couple of capacitors co uld make this work. I just was hoping someone could point me at a project o r could give me some hints on where to find such a project.

There are 1001 ways to do what you want. Here is a sketch showing a 555 circuit:

The 555 triggers when power is first applied and it's output goes high for 2-3secs. After that delay the output goes (and stays) low which activates the relay.

piglet

SPDT relay and small 2-3 second timer would do the job. I don't know where to get such a relay or timer, but using transistors and possibly a 555 see ms like a more reasonable solution.

switch no more.

guidance in making a solution for this problem.

automate.

uses this port for charging as well as USB OTG to connect USB peripherals. The problem is it won't usually charge while in OTG mode. Just applying 5v to the power lines of the USB port won't make it charge.. To get it to cha rge, you have to short the data+/- lines together. Then as long as you keep power applied to the Power +/- lines it will continue to charge without sh orting the data +/-. You can then connect usb devices to the data lines and the PC and they work.

it to be on an automatic timer.

vices at the same time. As it is now, I have to plug the usb hub in with th e SPDT switch in shorted position and then flip the switch every time I con nect the hub. I want to make it all automatic. It needs to have the lines s horted for a few seconds and then switch in the lines for the USB hub.

ound pin as a switch.. i.e. leave the ground wire disconnected in the USB c able. The shield wire is used to carry ground. When you plug it into the ta blet pc it connects the shield to the GND wire (since they are tied togethe r on the tablet's USB port) and completes the circuit.

t I would like to learn how to put to use. I am just starting out in buildi ng electronics.

problem solved. Use your parts for another project.

could make this work. I just was hoping someone could point me at a project or could give me some hints on where to find such a project.

You can do the RC at high impedance and use a darlington or sziklair pair t o run the relay.

NT

There are tiny pushbutton switches, like the ones used in front panel controls of virtually everything. Mount one on the USB plug and hold the swtitch while you plug it in.

I wonder how shorted together the data lines need to be to satisfy the protocol for charging. Maybe a 4066 quad switch and an RC time constant on the control line(s) would do the job?

Thanks everyone! I really appreciate all the advice and help.

I have a few ideas and things to try out now. :) Hopefully I can get this working in the next couple of days when I have a chance to get the parts.

Sounds like you need a bigger junk box.

NT