Need a certain type of switch that may not even exist.. - Page 1
Forum section: electronics / projects

author: DylanM
author_rank: Contributor
timestamp: August 24, 2012, 09:34:32 am
content: Hi all,I'm currently designing a power supply and have come across a tricky situation. I have 4 leads coming off a toroidal transformer that can be configured in parallel or series, to provide different combinations of voltage and current. This is great, however I would like to be able to switch between these modes without having to take the power supply apart and resolder things. So I designed a configuration to switch between parallel and series orientation, but for it to work properly I need a switch that can, on one setting, close two circuits leaving the other two open and vice versa. But the two circuits being switched on or off cannot make electrical contact (this would short out the transformer which is obviously a huge problem).A quick diagram might make this easier to explain:So my question is, does the kind of switch I'm looking for even exist? And if so, what is it called?Thanks

author: Balaur
author_rank: Unknown
timestamp: August 24, 2012, 09:56:28 am
content: Could I suggest you an alternative approach?The attached drawing shows how you can integrate the diode bridge in your solution. You can choose between a series (double the voltage) or alternate phase (doubling the effective current) configuration. You only need a single switch.A simpler approach of this is used in a lot of linear PSUs to select half or full voltage to minimize power dissipation.Cheers,Dan

author: Rerouter
author_rank: Super Contributor
timestamp: August 24, 2012, 10:18:50 am
content: here is the expensive approachhttp://au.element14.com/moeller/diler-22-230v50hz-240v60hz/mini-relay-2n0-2nc/dp/1109994and here is the cheap approachhttp://au.element14.com/multicomp/1m43t1b5m1qe/switch-solder-tag-4pdt-on-off-on/dp/155019401

author: Jimmy
author_rank: Regular Contributor
timestamp: August 24, 2012, 10:24:26 am
content: Google Roatry changover switch one way on on off fff middle off off off off other way off off on on then you mechanicaly can't short it out

author: DylanM
author_rank: Contributor
timestamp: August 24, 2012, 10:32:10 am
content: Quote from: Balaur on August 24, 2012, 09:56:28 amLooks good, I might use that. Although I'm a little confused as to how it works though.. Are the two connections in the center of the secondary of the transformer joined, and which orientation of the switch would be parallel and which would be series?Quote from: Rerouter on August 24, 2012, 10:18:50 amSo what I was looking for does exist.. Thanks for the response but after seeing Balaur's solution I may only need a standard switch now.Quote from: Jimmy on August 24, 2012, 10:24:26 amAgain, thanks. But it may no longer be needed, I'll look into it if the circuit in Balaur's post doesn't work for me.

author: Jimmy
author_rank: Regular Contributor
timestamp: August 24, 2012, 10:53:27 am
content: Np you didn't specify it was a dc power supply

author: DylanM
author_rank: Contributor
timestamp: August 24, 2012, 11:17:27 am
content: Quote from: Jimmy on August 24, 2012, 10:53:27 amHaha sorry, I thought it would just be assumed

author: DylanM
author_rank: Contributor
timestamp: August 24, 2012, 11:17:46 am
content: Quote from: Jimmy on August 24, 2012, 10:53:27 amHaha sorry, I thought it would just be assumed

author: Rufus
author_rank: Super Contributor
timestamp: August 24, 2012, 12:49:44 pm
content: Quote from: DylanM on August 24, 2012, 09:34:32 amAs I understand the problem you need the most common type of switch.

author: G7PSK
author_rank: Super Contributor
timestamp: August 24, 2012, 03:27:09 pm
content: 4 pole 2 way switch is what you need.