# Need to automatically switch a 12v 1amp dc pulse between 2 alternating outputs

I have a control unit that produces two 12v 1amp dc pulses lasting about 200ms. There is a gap of about 100ms between the pulses

I need to automatically switch these pulses between 2 outputs alternatly.

Any help would greatly appreciated

• what is your device for controlling? are you use micro controller? Are you use TTL palse for selecting? Please explain your needs for selecting two outputs. Sep 24 '12 at 5:21
• one output goes to one solonoid next output to go to another solonoid Sep 24 '12 at 14:20

Use a D-flipflop like the HEF4013 to switch between channels.

With each pulse the high level switches between $Q$ and $\overline{Q}$ and back. AND each output with the input pulse signal. Use the AND gates' outputs to drive MOSFETs like the FDC855.

The HEF4013 is from the older CD4000 series, and normally I would suggest the 74HC74, but that one can't operate at 12 V. The HEF4013 can operate at a power supply voltage up to 15 V.

Don't forget the protection diodes across the solenoids.

• Did you draw those schematics, if yes, using what? Sep 25 '12 at 15:19
• @abdullah - Adobe Illustrator. Sep 25 '12 at 15:22
• @abdullah - Illustrator is a fine software once you know how to use it. With "snap to grid" enabled is the timing diagram a question of minutes. As a matter of fact, the overscore over the "Q" was the most work :-) Sep 25 '12 at 15:59
• I am wondering if there are dedicated programs that will create timing diagrams. Sep 26 '12 at 6:41
• @abdullah - TimingDesigner, only 6500 dollar :-). Sep 26 '12 at 6:49

One solution for this is using multiplexers. A multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line.

For this i recommend use 74ls157. This is Quad 2-to-1 Multiplexer.

The operation of the 74LS157, Quad 2 line to 1 line multiplexer is quite simple. It simply acts as four switches. When the A/B input is low, the A inputs are selected. E.g. 1A passes through to 1Y, 2A passes through to 2Y etc. When the A/B is high, the B inputs are selected.

• "Paper out"???? This is multiplexer, but he needs a demultiplexer. This can't switch 12 V, and neither can output 1A. This is not a good answer. Sep 24 '12 at 14:52