Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.


View this topic in a long page with up to 500 replies per page Create new topic
1 | 2 
7386 posts

Uber Geek
+1 received by user: 2363

Subscriber

  Reply # 1523490 31-Mar-2016 18:09
Send private message

richms: People say that but I've not had a problem with 20+ amps on the 12v line and nothing on the 5 or 3.3v.

 

really depends on the power supply, some do some dont




121 posts

Master Geek
+1 received by user: 4


  Reply # 1524771 2-Apr-2016 19:22
Send private message

Jase2985:

 

mb82:
k1w1k1d:

 

The variable voltage is easy to do with one of these. I just unsoldered the blue 10k pot from the circuit board and ran wires to a 10-turn 10k pot on the front of the box.

 

 

 

http://www.ebay.com/itm/2PCS-150W-DC-DC-Boost-Converter-10-32V-12-35V-6A-Step-Up-Power-supply-Module-/400442480064?hash=item5d3c3b55c0

 


How do I calculate the current draw on the 12v rail to get 24v @ 5 amps on the output of the dc converter.

Also the pot you are referring to is that on the dc converter itself?

 

V=IxR or I=V/R or R=V/I

 

 

R=V/I , R=24/5, R= 4.8

 

I=V/R, I=12/4.8, I= 2.5    so 2.5Amp current draw at 12v to produce 24v @ 5 Amps?

 

I do not think I am doing it right?


 
 
 
 


Try Wrike: fast, easy, and efficient project collaboration software
20882 posts

Uber Geek
+1 received by user: 4094

Trusted
Subscriber

  Reply # 1524782 2-Apr-2016 19:42
Send private message

mb82:

 

R=V/I , R=24/5, R= 4.8

 

I=V/R, I=12/4.8, I= 2.5    so 2.5Amp current draw at 12v to produce 24v @ 5 Amps?

 

I do not think I am doing it right?

 

 

wrong formulas, wrong way around.

 

The power is the same, P=V*I, so 24v * 5 is 120 watts.

 

 

 

I = P / V  so 120 / 12 = 10 Amps

 

Then 10A multilplied by the inverse of the efficiancy so say 85% means

 

10 * (1/0.85) = 11.77 A

 

 

 

 





Richard rich.ms

20882 posts

Uber Geek
+1 received by user: 4094

Trusted
Subscriber

  Reply # 1524784 2-Apr-2016 19:44
Send private message

I would also not recommend any of the "boost/buck" converters for making an adjustable power supply. I got one and found the current limit became very very erratic when your in and out voltage was about the same, I cooked some 10w LEDs that way with it limited to 900mA fine when it was shorted or into a load that it clamped at well below 12v, but the series voltage of 3 LEDs is right around 12v and I had them start to pulse really brightly and blow after some time. 2 converters and about 6 LEDs later I decided to just use a buck only one and it didnt happen again, asked around and a few other people had seen the same thing happen.





Richard rich.ms

1 | 2 
View this topic in a long page with up to 500 replies per page Create new topic



Twitter »

Follow us to receive Twitter updates when new discussions are posted in our forums:



Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:



Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:





News »

Amazon launches the International Shopping Experience in the Amazon Shopping App
Posted 19-Apr-2018 08:38


Spark New Zealand and TVNZ to bring coverage of Rugby World Cup 2019
Posted 16-Apr-2018 06:55


How Google can seize Microsoft Office crown
Posted 14-Apr-2018 11:08


How back office transformation drives IRD efficiency
Posted 12-Apr-2018 21:15


iPod laws in a smartphone world: will we ever get copyright right?
Posted 12-Apr-2018 21:13


Lightbox service using big data and analytics to learn more about customers
Posted 9-Apr-2018 12:11


111 mobile caller location extended to iOS
Posted 6-Apr-2018 13:50


Huawei announces the HUAWEI P20 series
Posted 29-Mar-2018 11:41


Symantec Internet Security Threat Report shows increased endpoint technology risks
Posted 26-Mar-2018 18:29


Spark switches on long-range IoT network across New Zealand
Posted 26-Mar-2018 18:22


Stuff Pix enters streaming video market
Posted 21-Mar-2018 09:18


Windows no longer Microsoft’s main focus
Posted 13-Mar-2018 07:47


Why phone makers are obsessed with cameras
Posted 11-Mar-2018 12:25


New Zealand Adopts International Open Data Charter
Posted 3-Mar-2018 12:48


Shipments tumble as NZ phone upgrades slow
Posted 2-Mar-2018 11:48



Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.



Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.