DzlJim Posted February 5, 2007 Report Share Posted February 5, 2007 First off, I am pretty much electronically illiterate, though I'm quite handy and willing to learn.I have a project I need assistance with. I'll do my best to describe what I need.1) I need to convert 12v DC or 120v AC TO 110v DC. Must be DC not AC.2) I need an electronically controlled device that will open then close a series of 4 switches/triggers in succession. The closed time for each switch to be around 4 milliseconds, and it would be great if this was adjustable. If it needs to be a set value, no problem. Each switch is, in essence, transfering the 110v DC current to a device.3) I need this device to repeatedly open and close these 4 switches until it's told to stop. Time between the opening/closing of each switch is variable (I have no set requirement for this) though it might be controlled by 4).4) I would like for this device to be able to control how many times per minute the group of 4 switches can be opened and closed, kind of an RPM value.5) Device would have a Power in terminal (then convert to 110v DC?), Ground terminal, and 4 Out terminals one from each switch.Hope this makes sense. Can anyone tell me if this is possible/practical to do?Thanks for any help,Jim Quote Link to comment Share on other sites More sharing options...
ante Posted February 6, 2007 Report Share Posted February 6, 2007 Hi Jim,I don Quote Link to comment Share on other sites More sharing options...
DzlJim Posted February 6, 2007 Author Report Share Posted February 6, 2007 I tried to keep it in simple electronics terms, but I'll give it a shot what the actual project is:I need to test Diesel Fuel Injectors that are electronically actuated. They require 110v DC to operate.Picture a cylinder head from a V-8 Diesel, thus 4 cylinders/4 Injectors.I need to fire the 4 injectors, in sequence NOT at the same time (for other reasons). I need to do this electronically/automatically. Id like to vary the 'On' time, or Pulse Width as it's called, and I need to control how many 'Injections' per minute, or how many times the 4 injectors fire in one minute. OR determine (variable, knob?) how many 'Injections' they are to do, period. Like 100, 500, or 1000.I can rig up a motor with a cam and microswitches and stuff, but that's too hokey for me. I'd rather have an electronic control panel that is capable of doing everything.Make more sense?Thanks for any help. Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 6, 2007 Report Share Posted February 6, 2007 Use a 4 stage counter driven by a clock. Use the counter outputs to trigger 4 separate monostables. The time constant from the monostable can be varied with a pot. Each monostable can fire a power fet to switch the injectors. The clock could also be varied with a pot. This is the idea, now remaining are the details.Think 555 clock, 4017, counter, 4013 monostables etc.. Quote Link to comment Share on other sites More sharing options...
DzlJim Posted February 7, 2007 Author Report Share Posted February 7, 2007 Thanks for the response.I must reiterate how electronically illiterate I am. I have no idea what you just said, but it sounds simple enough.Would it be possible for you to maybe give me part numbers from an online supplier so I can figure out what you're refering to?Or (I don't want to break any rules here) is this something that you'd be willing to build for some form of compensation?Thanks. Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 7, 2007 Report Share Posted February 7, 2007 Here is your basic circuit. R4 adjust the firing rate per minute. R2 adjust the time the pulse will be high. The pulse out will drive a FET to switch the injectors. R5 will determine the minimum on time of the pulse. R6 will set the maximum clock rate.From the pictures: top trace is clock, next is the (1 of 4) counter outputs to the monostables. Only 1 monostable shown. You will have to duplicate 3 (the 4013 section and parts D1, R5,C1,R2) more. Bottom trace shows the output pulse from the monostable. You can see how the firing rate and pulse width changes with adjustment of the pots. One will have to select the values so that the max on time of each monostable is shorter that 1 period of the clocks signal so only 1 injector fires at a time-fixed in last modC2 can be shorted and R3 removed, just I have a habit to provide short reset pulses which makes debugging more complex circuits easier.You will find all these parts at www.digikey.com Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 7, 2007 Report Share Posted February 7, 2007 Here is a modification to prevent the on-time from exceeding the clock period if the clock rate is made faster. This will prevent 2 injectors to be on at the same time. Quote Link to comment Share on other sites More sharing options...
DzlJim Posted February 7, 2007 Author Report Share Posted February 7, 2007 Thank you so much for the input.I actually have a digikey catalog, so now I need to chew on this stuff and see if I can digest it all! Quote Link to comment Share on other sites More sharing options...
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