Advice on bypass/AB/Y selector?

That is the link for an AB/Y selector i TRIED to build. The idea is that the input can be sent to either A or B or A and B. I followed the instructions, but I was unsure about which side of the switch is which. They were DPDT switches. I built the one of the top without LED's. I configured it so that if the switches were see-through, then the top left connector in the diagram would have been the top left if the button on the switch was facing up and all the connectors facing down. Maybe this is wrong, maybe there is a certain way to read these things. This is my third project with soldering that i have done and it is the first that failed so im pretty sure this will be simple stuff for most of you. Also, if you have any good links to a forum that tells how to read those schematics with the electrician style symbols of everything cause i found a few plans with that layout but had no idea how to read it. sorry if this post is a little long but hopefully someone can help me out. thanks.


2002-12-23 11:22 pm

I am not 100% sure of the question here from your description, and haven't read what kind of switches are intended here, but maybe the following might help.

The diagrams look as if they are the contacts on double pole double-throw (or changeover) switches, most likely toggle switches. Each side is independent, and that is why on the leftmost switch (A/B changeover), there is a separate external connection added between the top L contact and the lower R contact, and the same between the top R and the bottom L.

With such toggle switches, when you move the lever downwards, it will internally connect the middle and TOP tags on both sides of the switch, and when the lever is in the upper position, the BOTTOM and middle tags are internally connected. I know that this may not be intuitive, but with every similar switch I have ever seen (hundreds) this is the way they work, and is a result of their construction. Although both sides of each switch will changeover at the same time, there is still no internal connection from one side of the same switch to another.

What may help is if you separately draw out the routing of the connections with the switches in each position, based on what I have said above. i.e. draw the first rough sketch as if the lever is upwards on the first switch (or with the internal connections on both sides being made between the middle tags and the lower tags) and then do the same with the lever in the opposite way, and hopefully then you will see how the *external* circuit connections are changed over.

I hope this helps.