Backyard Aquaponics
A place to discuss aquaponics

Suppression caps really do something after all.

I'm playing with motors and transistors, and had the motor oscillating between on and off at a pace like you might be able to do tapping the wire to the motor as fast as you can. It was driving me nuts until I remembered the cap across the motor terminals. I had the post asking for help ready to go when I thought to myself ~ What would SuperVeg, and nebbian say? ~

I just solved my first problem all on my own






~Thought quotes

woo !

What happened to this thread? I was learning!

A friend bought a device to turn 12v into anything from 12v-60v and it has two pots and two pairs of terminals marked CC (constant current) and CV (constant voltage).

What are constant current power supplies for?

I was under the impression that a device would draw the amount of current it required.

Powering LEDs and charging batteries are the two most common uses I can think of. There are others.

Cool, thanks.

I told him "charging batteries maybe", so I must actually be learning stuff after all this time

Your impression is dead right, but unlimited current.. ie. What it wants .. can be damaging to life expectations ..

Constant Voltage allows variable Current
Constant Current allows variable Voltage.... any voltage that causes the set current

A device like that is likely intended for LED use, where you either need a set and constant.VOLTAGE, because the led device limits the current using internal resistors etc... OR
when the led has no resistors and demands a.constant limited current and the voltage just adjusts to ensure the constant current...


Eg.. I am reliably told that a typical 12V led will fail prematurely, when connected to a typical floated 12V battery.. which will be an actual 13.8V, causing a significant overcurrent to the led's

In normal use the device is likely not completely practical, other than as a constant voltage supply..
Connected to a battery system, it would mean the output would be constant, whereas the input would vary according to the. StateOfCharge of the battery ..

Constant current could be good for resurecting a damaged battery, where you could set the current to C/100 and let it do it's best.
It will punch the voltage up high to get the current flowing and as the battery changes condition, the voltage will then drop to normal, whilst the current always remains c/100.. when (and if) the voltage reads normal, then. You are ready to really exercises it and see if it can be used reliably...

I've done this with LA batteries suffering sulphation with varying degrees of success..
C/100 is generally a charge rate that most batteries can sustain safely for a long time

BTW... another way that constant current might be practical, is for when you need to run a known device over a deficient sized cable.. eg.. you know the light needs 50mA, and so the voltage will rise until 50mA is flowing, irrespective of the voltage drop over the long wire run.. not necessarily practical, but possible..
Constant Current to a motor might not work as the START current could not be satisfied, butt it would run once started..
..
.

the device is a 12-60v power supply advertised on ebay for powering laptops directly from your car.

In this case, the hope is to boost the voltage to a pump that runs fine when the [s]o[l]ar charge is in topup mode, but doesn't do so well when it switches to float. so... from 14.3v down to 12.6 or something. So if constant volts is set to 14.3 we should be all good with the extra current required at start.

Yay!

if the current isnt enough, I think I can just add a large capacitor between the device and the pump.

..
Perhaps it could be good to start again .. and better describe the full application..
What is the pump and it's power needs and what do you want to power it from..

My initial thought is you need 14v from a 12v source..
..
.

Yes that's correct. 14v from 12v

Device = 12v input to 12v - 60v output power source advertised to power a laptop (probably 19.x volts) from a car's accessory plug (lighter plug)

Pump = a 12v solar pump connected to a 200 amp hour lead acid battery bank. When the solar is charging, the battery voltage is up around 14.3 or similar, and the pump works fine.

When the batteries are off the charger (night time or whatever) they sit at around 12.6v. At 12.6v the pump doesn't work so well.

I'm guessing it's probably designed to run from a starter battery in a boat as a bilge pump or as a live bait tank pump.

.
So 12v solar pump.. I do wonder what that means.. pure 12v or solar charged battery.. kinda irrelevant..
I'm guessing that you have.found the obvious, that fourteen is better than twelve.. ie. 15% higher

Constant voltege then, should be good, as it will adjust the current to suit..
When working, measure the. voltage at the pump and perhaps readjust to allow for line loss..
A generous capacitor across the start of the cable could help with motor start surge..

Give us a link to the device on ebay.. curious if also on Alibaba...
( just love Aliexpress - buying new things.every day. :-).. :-) )
..
.

It's generally a bad idea to post an ebay link to a forum because in three weeks it wont help anyone because the item will no longer exist so...

if you search for "http://www.ebay.com.au/bhp/dc-dc-converter-step-up" and look for an image with the coil lying flat in the middle, and two caps on either side... that will be the unit. There are also terminals on each side. Two on one side, and four on the other. 12-60v output 150w 8amps from memory.

I think I'll add one to the torch I'm building for my River Murray adventure as an any-volts adjustable output plug to recharge a phone or whatever.

The link no longer exists, but it looks a lot like this at time of writing... http://www.ebay.com.au/itm/150W-8A-DC-8 ... 1211559869

As far as I know its working fine now.

Now I have to convince him to make a new boat.

Tricky.

I figure it will unfold something like this...

Me - Your hand-made floating home isn't cool enough (Thanks for inviting us on board again).
Him - !

A cool app I like to use with my electronic projects is electrodroid.

Nice!

Did you make it?

If so, pvt me. I want to talk about a business opportunity.