Power supply problems

  • #1
Anugrah_kora
5
0
I've got an old laptop charger 19v 3A for my solenoid.
I used a multimeter to check the charger without and with load. I used a solenoid of insulated 22gauge of approx 150 turns as the load. On my first try without any load, it gave 20v DC on the multimeter.
When I connected the load and connected the multimeter ,it gave values on AC part fluctuating back and forth from 0-1.5v . Can anyone help me out in this? Is there anyway to get DC out of it while on load ?
 

Answers and Replies

  • #2
berkeman
Mentor
63,238
14,184
I've got an old laptop charger 19v 3A for my solenoid.
I used a multimeter to check the charger without and with load. I used a solenoid of insulated 22gauge of approx 150 turns as the load. On my first try without any load, it gave 20v DC on the multimeter.
When I connected the load and connected the multimeter ,it gave values on AC part fluctuating back and forth from 0-1.5v . Can anyone help me out in this? Is there anyway to get DC out of it while on load ?
You are shorting out its output, so it is in current limit until you remove the short.

You need to put a load of about 19V/3A = 6.3 Ohms on it to keep it out of current limit.
 
  • #3
Anugrah_kora
5
0
You are shorting out its output, so it is in current limit until you remove the short.

You need to put a load of about 19V/3A = 6.3 Ohms on it to keep it out of current limit.
I tried 6ohms ( I don't remember correctly,but it's close to 6ohms) and the solenoid literally ceased to function :(
 
  • #4
berkeman
Mentor
63,238
14,184
I tried 6ohms ( I don't remember correctly,but it's close to 6ohms) and the solenoid literally ceased to function :(
What wattage resistor did you use? I^2 * R = 54W, so you would have needed a pretty big power resistor...
 
  • #5
jim hardy
Science Advisor
Gold Member
Dearly Missed
9,869
4,891
#22 is 16 milliohms per foot.

How many feet of #22 would it take to make six ohms ?
On your solenoid's diameter, how many turns would that be ?

Do you understand the relation between amp-turns and magnetic field strength ?
You might look that up . Train your search engine - it wants to please .
 
  • #6
davenn
Science Advisor
Gold Member
2021 Award
9,623
8,831
I tried 6ohms ( I don't remember correctly,but it's close to 6ohms) and the solenoid literally ceased to function :(

not surprised .... your LOAD, the coil, needs to be around 6 Ohms ... not a 6Ohm resistor in series with it :smile:


Dave
 

Suggested for: Power supply problems

Replies
10
Views
214
  • Last Post
Replies
7
Views
287
  • Last Post
Replies
19
Views
143
Replies
7
Views
218
Replies
7
Views
598
Replies
33
Views
889
  • Last Post
Replies
23
Views
376
Top