Salvaged air compressor from Stanley Fatmax Jumper

Thread Starter

Teljkon

Joined Jan 24, 2019
173
Maybe I didn't say what goal was clearly enough. First i want to use a bread board to run the air compressor off of my power supply that I converted from a old PSU. Other members helped me figure out that my old PSU saw such a large draw as a short. That will really just be to learn more about circuits. Second I am going to use Lithium Ion batteries and a standard laptop 12v charger to power & charge the pump sans PSU.

I am adding a step for education. dose that make sense now.

P.S. Some people may find your name a little placating.
 

wayneh

Joined Sep 9, 2010
16,399
A breadboard has small conductors and isn't meant for the level of current your compressor requires. But above and beyond that I don't understand what kind of circuit you might be wanting to experiment with. Your compressor needs to connect directly to a power supply that can drive it. There's nothing you can do with a circuit that can change that. I'm not sure a typical charger is beefy enough, but maybe. Be careful with lithium batteries; charging them improperly can cause them to literally explode.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
173
So basically I just need to get some Lithium ion batteries and a suitable charger then. the capacitors are moot. That dose not make any sense though a capacitor functions like a battery. If not a singular capacitor one capacitor than a series of capacitors could hold enough charge to up my current. I may only get intermittent running but still it should be enough to learn about them. The point isn't that it makes sense the point is to understand current vs voltage an how that relates to capacitors. I guess I will proceed without your help then. Thanks anyway.
 

wayneh

Joined Sep 9, 2010
16,399
Capacitors have their uses but supplying lots of power for extended time isn’t one of them. Compared to batteries they are expensive and large, and require circuitry for proper charging and discharging. Unlike a battery the voltage on a capacitor drops steadily as it discharges.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
173
You really want to go there??

Disagreeing with what you seem to think a capacitor can do is not a personal attack, no matter what you think.

Yes I do really want to go there. you are correct your name being placating has nothing to do with what capacitors can do or cant do. It has every thing to do with you, in all likely hood, being a cyber bully/hothead. I've run into your kind before nasty name nasty an no patience for what you see as the incompetence of others. I came here to learn, and i think in a unorthodox manner, so I will probably annoy you at every turn. I have an easy solution for you just don't respond to my posts. There are others here who don't seem to mind teaching a little. Even a guy who is a little off center, to you, such as my self. I am sure they can help me an we will all be better off for it.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
173
Capacitors have their uses but supplying lots of power for extended time isn’t one of them. Compared to batteries they are expensive and large, and require circuitry for proper charging and discharging. Unlike a battery the voltage on a capacitor drops steadily as it discharges.

I grabbed some of the above kits and I am also getting a few super capacitors so between the lot I am sure I can make it work some how. 2.7V*10 can be 27 volts the farads may be a little low but it should work. I also got some 100 farads ones cant remember the volts but again I am sure i can make some thing on the bench jump to life. It should be an interesting little project to learn on and all the parts should work in other projects down the road.
 

shortbus

Joined Sep 30, 2009
7,912
Yes I do really want to go there. you are correct your name being placating has nothing to do with what capacitors can do or cant do. It has every thing to do with you, in all likely hood, being a cyber bully/hothead.
Well I bow to the guy using a starwars reference for his screen name. I wish I'd thought of something original like that. There is an old thread here that we explained our choice of screen names. And mine is nothing like you have decided. And you joined too late to meet the cyber bully that was here.

And I said nothing different than what wayneh told you, that caps aren't batteries and don't work as you want them to. You were told that earlier in this thread and refused to believe it, but that's because you think differently I'm sure. Have you even done any research and looked at the charge discharge curve for caps? You will be surprised when this doesn't work out as your different thinking is futile.

And I'll post in what ever thread I like, thank you.
 

wayneh

Joined Sep 9, 2010
16,399
I'll just add to please be careful both for yourself but also for your capacitors. They're not cheap and they are unforgiving about being damaged if they see over-voltage. If you place them in series to achieve a higher voltage, you need to address keeping them balanced. Otherwise, the voltage won't necessarily distribute equally across them and you could end up ruining oner more of them. Accidentally shorting a capacitor can allow a very large current to flow, resembling shorting a car battery. If you've ever done that, you see that it can be dangerous.
 

wayneh

Joined Sep 9, 2010
16,399
@wayneh, do you really think that the caps will run this compressor?
No, not for more than a revolution or two. He'll need to carefully charge them to their max voltage in parallel or one at a time, then wire them all in series, then apply to the motor.

The only valid role I see for capacitors here is to supply that initial current boost to get the motor spinning, potentially allowing a slightly smaller battery. There are automotive batteries out there that incorporate a portion of their capacity in ultra capacitors. They're allegedly useful in really cold weather to get the starter cranking.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
173
No, not for more than a revolution or two. He'll need to carefully charge them to their max voltage in parallel or one at a time, then wire them all in series, then apply to the motor.

The only valid role I see for capacitors here is to supply that initial current boost to get the motor spinning, potentially allowing a slightly smaller battery. There are automotive batteries out there that incorporate a portion of their capacity in ultra capacitors. They're allegedly useful in really cold weather to get the starter cranking.
Well my PSU was able to get a few turns out of it just hooking it up directly so we shall see. That is the fun though. If I fail with just the diods and capacitors I will still have learned something. For example i don't understand why capacitors are considered AC I mean i get that they charge all the way up then discharge I learned that while watching videos on 555 timers on a 8 bit bread board computer. I currently think of them as a bucket that fills up then dumps it contents back into the circuit. Is there any flaw in my thinking. I am actually thinking of using the two other pegs on my PSU as well. No reason I cant use the five volt and 3 volt pegs to drive it as well. That's 19v now if I can turn all that into current and push it threw a diod so what ever short circuit sensor is in my PSU dose not get tripped! I think I stand a chance.
 

wayneh

Joined Sep 9, 2010
16,399
Capacitors are not AC or DC, as you noted they are like a bucket in some ways. It’s true that an AC signal can be passed by a capacitor while a purely DC signal quickly charges the capacitor and no more current will flow.

Proceed slowly and carefully with your experiments. Your power supply was probably not designed to do what you described.
 

wayneh

Joined Sep 9, 2010
16,399
This is interesting.

https://www.electrical4u.com/voltage-to-current-converter/

As is this.

https://en.wikipedia.org/wiki/Operational_amplifier

Why cant I just use an op amp with some resistors while pulling voltage for all my pegs. I have 20v there that I can use to up the current. Perhaps I don't understand the math so that's the next rabbit hole.
Forget the math. The problem is with the energy balance. Op-amps are very cool but they don't create energy. Any and all power coming out of an op-amp is supplied by the power supply connected to it. So if you really want power, just drop the op-amp and connect directly to the power supply.

I think of op-amps as manipulating information, not power. They work in the milliamp range. Of course you might find "power op-amps" that blur the distinction, but even those don't handle the kind of current you need.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
173
Forget the math. The problem is with the energy balance. Op-amps are very cool but they don't create energy. Any and all power coming out of an op-amp is supplied by the power supply connected to it. So if you really want power, just drop the op-amp and connect directly to the power supply.

I think of op-amps as manipulating information, not power. They work in the milliamp range. Of course you might find "power op-amps" that blur the distinction, but even those don't handle the kind of current you need.

Kinda get what your saying but it seems an op amp can up the voltage or current in a circuit at the expense of the other. So why if I have spare voltage can't I convert that to current. Remember I believe what you said is correct that the PSU is using some kind of short protection. The motor did give a crank if i put the leads directly to the motor. A diod is a one way valve so if I am not far from getting it going it seems logical that i should be able to get it going with excesses converted current and a diod. I wish i could give details on the motor but it is not stamped any where. Its not that big about the size of my hand long and no bigger than a silver dollar. If no current flows in back to the PSU then how can it trip the short protection? these are all of my simple conclusions that lead me down this road.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
173
While I am at it why dosen't any current flow threw the two op amp leads are there any cut away's of op amps?
 

wayneh

Joined Sep 9, 2010
16,399
Kinda get what your saying but it seems an op amp can up the voltage or current in a circuit at the expense of the other. So why if I have spare voltage can't I convert that to current. Remember I believe what you said is correct that the PSU is using some kind of short protection. The motor did give a crank if i put the leads directly to the motor. A diod is a one way valve so if I am not far from getting it going it seems logical that i should be able to get it going with excesses converted current and a diod. I wish i could give details on the motor but it is not stamped any where. Its not that big about the size of my hand long and no bigger than a silver dollar. If no current flows in back to the PSU then how can it trip the short protection? these are all of my simple conclusions that lead me down this road.
Current flows in a loop, a circuit. If you use a diode to block current it can do that, but it will block all current throughout the circuit. I see no role for a diode in what you’re doing.

Regarding opamps, they can assist in converting current to voltage or vice versa but only at tiny power levels and only within the capacity of the power supply attached to the op amp. They can’t really help at significant power levels.

An opamp won’t draw hardly any current whatsoever if it has no load on its output. If you attach an LED and resistor that will draw 10mA when powered up, the opamp will draw roughly 10mA from the power supply when the inputs to the opamp are configured to turn on the LED.
 
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