How to increase current in a circuit

Status
Not open for further replies.

Mijanur Rahman

Jul 12, 2015
5
Hello everybody,
I need your help please. I have a step up circuit that step up only voltage like 3.5v input to output 5v(1200mA) DC-DC booster circuit. It takes greater input current than output current. But i need only greater output current. I mention again i need to use lower input current and greater output current. I found online that 555 timer circuits increase output current. Here is the link http://www.555-timer-circuits.com/increasing-output-current.html
So can anybody tell me how to set up this circuit to increase my output current? I am new in electronics. This link dont show the proper circuitry like where to start positive and negative terminal. And also tell me how to join this circuit with my step up circuit. In this link you will see some specifications for output current. I need 3A - 5A using a BD679 or equivalent with heatsink. This current is perfect for my project. So please anybody help me.
Thanks,
Mijanur Rahman
[email protected]

Arouse1973

Dec 18, 2013
5,178
But thats how a booster works. So what you are saying is you need a boost circuit that boost voltage but the input current needs to be the same as output current?

Mijanur Rahman

Jul 12, 2015
5
But thats how a booster works. So what you are saying is you need a boost circuit that boost voltage but the input current needs to be the same as output current?
Well as it boost only voltage can not it(or any other circuit) also boost current? or can i use any other circuit either in series or parallel to increase output current?

Arouse1973

Dec 18, 2013
5,178
For it to boost voltage it requires current, the input current can be more than output current.

davenn

Moderator
Sep 5, 2009
14,150
Well as it boost only voltage can not it(or any other circuit) also boost current? or can i use any other circuit either in series or parallel to increase output current?

no, you are limited by the current supplied to the input by the source
you cannot boost voltage and current .... that breaks the laws of physics

If you need more output current, you need a source that can supply at least that much current + a bit more
as there will be losses in the converter. Nothing is 100% efficient

Dave

Mijanur Rahman

Jul 12, 2015
5
no, you are limited by the current supplied to the input by the source
you cannot boost voltage and current .... that breaks the laws of physics

If you need more output current, you need a source that can supply at least that much current + a bit more
as there will be losses in the converter. Nothing is 100% efficient

Dave
Dear sir,
I know about conservation law. I dont violate that. I say like my step up circuit give me 5v and 1200mA output whatever it uses in input. Now i intend to add any other circuit that only increase current either in series or parallel. As well i want 5v fixed in output just help me to increase current. Only i want to increase current any way adding another circuit.
My step up circuit is

http://www.tmart.com/5V-3A-DC-DC-No...Voltage-Module-for-Circuit-Board_p214903.html
Or
http://www.alibaba.com/product-deta...c10ce6d72ae3c&smSign=5zLefegTbiEOjMHpQSlHmQ==

But i don't how much input current does this circuit take? I know only the voltage this step up circuit use as 2~5v and 3~5v input respectively. Here i want greater output current any way either using additional circuit in series or parallel. Do you know this step up circuit use lower input current or higher than output current?
And here is a circuit that claim it can increase current. http://www.555-timer-circuits.com/increasing-output-current.html
Can you help me how to add it with my step up circuit to increase current?

davenn

Moderator
Sep 5, 2009
14,150
I know about conservation law. I dont violate that. I say like my step up circuit give me 5v and 1200mA output whatever it uses in input. Now i intend to add any other circuit that only increase current either in series or parallel.

well if you understand the laws of physics, then you will also understand that you cannot do what you are saying

unless
A --- you sacrifice voltage or
B --- you do what I said in my last post and have a source that can supply more current

for your last link with the 555 times, it ISNT increasing the output current of the 555
rather the low output of the 555 is being used to drive a transistor that is connected to a higher current power source. This ISNT what you want or need

BobK

Jan 5, 2010
7,682
If we could boost both voltage and current at the same time, we could run everything off a button battery!

Bob

davenn

Moderator
Sep 5, 2009
14,150

OK the first one .... the 5V 3A unit it will need a minimum of 3V and 3.5A to get your 5V @ 3A out of it

The second one .... to get 5V and 1200mA (1.2A) out you will need a minimum input of 3.5V and 1500mA
A 3.7V 2000mA (2A) LiPO cell would be ideal

Mijanur Rahman

Jul 12, 2015
5
OK the first one .... the 5V 3A unit it will need a minimum of 3V and 3.5A to get your 5V @ 3A out of it

The second one .... to get 5V and 1200mA (1.2A) out you will need a minimum input of 3.5V and 1500mA
A 3.7V 2000mA (2A) LiPO cell would be ideal
Ok sir you did not answer me one thing. Say if for second one i get 5v and 1.2A out from 3.5v and 1500mA input then can i use the other circuit http://www.555-timer-circuits.com/increasing-output-current.html to increase current adding it with step up circuit either in series or parallel?

AnalogKid

Jun 10, 2015
2,701
No. You are confusing increasing the output current *capability* of a low power device with an amplifier (the 555 circuit), with increasing the output current available from an energy source (like a boost converter).

Here is how to estimate the relationship between input current and output current of a power converter like a power supply or a boost regulator. In your case the output voltage is 5 V and the output current is 1.2 A, so the total output power is 6 watts. Divide this by the efficiency of the converter circuit. Yours runs at 500 kHz, an indicator of an above-average circuit, so we'll assume 80%. 6 divided by 0.8 = 7.5 watts. this is the total input power. Now divide this by the input voltage to get the input current. 7.5 / 3.3 = 2.28 A. Remember that this is a *power* converter. If the voltage goes up, the current goes down (and vice-versa). For the same input and output voltages, the only way to get more output current is to use a circuit that can handle more input current.

ak

Mijanur Rahman

Jul 12, 2015
5
No. You are confusing increasing the output current *capability* of a low power device with an amplifier (the 555 circuit), with increasing the output current available from an energy source (like a boost converter).

Here is how to estimate the relationship between input current and output current of a power converter like a power supply or a boost regulator. In your case the output voltage is 5 V and the output current is 1.2 A, so the total output power is 6 watts. Divide this by the efficiency of the converter circuit. Yours runs at 500 kHz, an indicator of an above-average circuit, so we'll assume 80%. 6 divided by 0.8 = 7.5 watts. this is the total input power. Now divide this by the input voltage to get the input current. 7.5 / 3.3 = 2.28 A. Remember that this is a *power* converter. If the voltage goes up, the current goes down (and vice-versa). For the same input and output voltages, the only way to get more output current is to use a circuit that can handle more input current.

ak
Dear sir, i can not understand your last sentence. For the same input and output voltages, the only way to get more output current is to use a circuit that can handle more input current. could you pls clarify if i have a hope from this sentence? or is there no other way in electronics?

AnalogKid

Jun 10, 2015
2,701
Both of the parts you had links to are non-isolated boost DC/DC converters. Basically, the circuit is one storage inductor and two switches. The input switch connects the inductor to the input to charge it up. Yes, you can charge up an inductor very much like you charge up a capacitor, except that an inductor stores the energy in a magnetic field while a capacitor stores the energy in an electric field. Then the input switch is turned off, the output switch is turned on, and the energy is transferred to the output filter capacitors. Usually the output switch is just a rectifier diode, but it acts as a switch none the less. There is a controller IC that runs everything, adjusting the timing of the input switch to compensate for changes in the output voltage and current. That is the basic circuit operation.

The input switch device, the controller frequency, and the inductor size and resistance limit how much energy you can store in the inductor. If you have a circuit that can handle a maximum of 3 A input current, the only way to get that circuit to handle more current is the change several of the components - basically, re-design the circuit.

ak

davenn

Moderator
Sep 5, 2009
14,150
Ok sir you did not answer me one thing. Say if for second one i get 5v and 1.2A out from 3.5v and 1500mA input then can i use the other circuit http://www.555-timer-circuits.com/increasing-output-current.html to increase current adding it with step up circuit either in series or parallel?

I did answer the 555 thing in post #7

davenn

Moderator
Sep 5, 2009
14,150
OK,
you have been told several times that you cannot boost current in the way that you think or want

please reread all the answers given to you ... ALL the info you need is contained within them

Regards
Dave

Status
Not open for further replies.

Replies
6
Views
988
Replies
4
Views
1K
Replies
3
Views
1K
Replies
3
Views
874
S
Replies
6
Views
1K
Randy
R