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need a "little" help

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deschlayer

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I am trying to make I timed varyable voltage dc power supply. here what it has to do:
1- vary voltage from 1-12 volts dc.
2- allow me to adjust the top end voltage
3- allow me to adjust the bottom end voltage
4-allow me to adjust how long it take to get from say 2volt to 12 volts(like to have a range of 10 seconds to 2 min)

if someone could point me in the right direction as to how to go about leaning how to make this, or has a link to a device simarler to this that would be great. any help is greatly appresiated
 
point me in the right direction as to how to go about leaning how to make this
Look into OpAmp circuits. An integrator, buffer and a pair of OpAmp precision rectifiers will probably do what you want.
 
I have been able to read about the opamps, but the buffer and others i cant google, is there a more specific name for the other parts? and just to add I know nothing about electronics exept how to soider, am I in over my head or is this something that I will be able to read enough about to build?
 
There are lots of details you left out, like how much current the load draws, how you are going to trigger the start of the ramp, what happens after it times out, etc.
Why don't you just tell us what you are trying to do?
 
current is from 0.6 watt to 13.7 watt I want it to contiualy go from the adjustable low point to the adjustable high point, and just loop this in the adjustable time frame, withch I would realy like to have even more range, like from 2 sec to 2 min then up to a couple hours. Idealy I would like it to have two dc outputs that are doin exactly the opisite of each other. to explain what it is: It is a dc powerhead controler to simulate waves in an aquarium.
 
so If i take a LM317 and put the adjutment resister from 100 to 2k then it will oporate from 1.7 to just under 12 volt. is there a way to make or buy a sweeping resiter that has an adjustable bottom and top range that can be adjusted for sweep time?
 
I have backed off from this because it looks like a big project that I don't have enough time to devote to. Perhaps others can help, but anyone who does needs a lot more info:
You gave the current requirements in Watts. Watts is a power measurement. Current is measured in Amps. Can you point to a datasheet of the device(s) that you need to control? "Powerhead" is noninformative.
I'm guessing the current requirements would make this a candidate for pulse width modulation (PWM), but we won't know until we know what sort of device you are controlling (motor, solenoid, etc.).
A microcontroller is probably the ideal part to use as your controller. Do you have experience with them?
If you don't use a microcontroller, it could concievably be controlled with an oscillator, a counter, some logic gates, a D/A converter, and either a PWM circuit or a linear driver, again depending on the load.
You need to post detailed ideas on how you want the control voltage vs time to look.
God knows what other questions will come up.:confused:
 
I cant get a data sheet, where as I cant find one. the current is 310 milliampere. a powerhead is an under water pump that does not "pump" water just simply moves it at a certain flow rate eg 400gph. it is basicaly an imperler that is housed in a cage with no direct flow just a direction of flow.
it is a motor. as far as voltage vs time. I want it to surge from one voltage to the other and then back again repeting, with all three point being adjustable. eg. "2" volt, to "12" volt, over "30" seconds.
as far as everyones help, I am very greatfull, and has provided me with alot of reading witch I beleiv is pushing me in the right direction :)

I think another name of what I am looking to build would be a Voltage sweep generator
 
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The drawing below has 4 variables, not 3. Are you implying that one of the time values doesn't need to be variable?
 

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yes. the amount of time it take to go back down to V1 can be the same as the amount of time it take to get to V2. of couse having 4 points of adjustment would work just fine if not perfered, i would not want to over complicate this device. unless there is a schematic already in existance of one such device.
 
I started on a design, but I began wondering about your basic concept. The ramps you propose will result in increasing water velocity, then decreasing velocity, but always in the same direction. It seems to me that the direction would need to change periodically, and maybe the velocity should be constant instead of ramping. Comments?
 
The constant changing creates different levels of flow at all times. Thrashing the corals/fish around the tank in a more "ocean like" way. The idea is I will make two controllers to run two power heads on opposite sides of the tank, and have them run bipolar of each other eg. When the one on the right is ramping up to 1000gph the one on the left will be ramping down to 300gph. short ramps onder 5 seconds would simulate wave like movement, wilst long ramps of 4 hours to 6 hours would simulate tides going in and out. more water would be moving from left to right for "high" tide. then more water would be moving from right to left during "low" tide. in the latter I would make a 3rd device that would controll a powerhead in the center of the tank runing a short ramp to "break up" the water movement and add surging current to the constant increasing or decreasing flow from either side.
 
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