Tagged Questions

3
votes
1answer
75 views

Possible measures to make power supplies safe

I'm looking for a list of ways that mains-powered ELV power supplies with touchable terminals can be made safe in the case of transformer failure with primary and secondary coils becoming connected ...
-2
votes
1answer
99 views

Why UPS for sensitive SMD development?

My friend suggests me UPS for SMD development. I already have a a surge protector over all devices. He recommended the UPS that transmit all energy through its battery and he recommend to find some ...
3
votes
3answers
155 views

Building a power supply, want to stay alive

I am building a power supply for a very old laptop. The circuit uses a transformer (220 V primary to 15 V secondary, 33 VA) and that worries me a little. (Please note that I an enthusiast and so far I ...
24
votes
1answer
354 views

What is / how can I get a student-safe power supply for electronics projects?

What is / how can I get a student-safe power supply for electronics projects? I'm looking for a student-safe power supply for solder less breadboard. I'm developing a course to teach electrical ...
2
votes
2answers
1k views

Grounding a DIY power supply

I am trying to develop a bench power supply. Now, before going on, I do realize that there are really cheap commercial ones available. I have two. I want to develop one my self. The way I have ...
3
votes
1answer
95 views

Safely testing a DC supply with an unknown output configuration

This picture shows the connector for the DC end of a power supply I extracted from a dead HP MFD (Multi Function Device): As you can see it consists of 4 pins in a 2x2 configuration. The sockets ...
3
votes
2answers
863 views

Safe to add a switch into power cord?

First off: I realize that my problem could be solved by simply using a few power strips with built in on/off switches, but I do not want to do that. I look at this project as being a learning ...
4
votes
1answer
585 views

AC->DC supply, how to deal with chassis ground being connected to digital ground?

I have an external triple-output AC-DC supply with the following output pinout: On the power supply, "ground" (pin 2) is internally connected to the ground wire of the mains plug. I'll refer to it ...
0
votes
2answers
536 views

Dual polarity power supply for project, possible choices?

For a variable power supply I require 15V to get ~0-12V, and +/-15V for an op amp as part of the project requirements, also negative rail in the future. Two plugpacks (isolated, 15/0/-15)to me seems ...
1
vote
1answer
420 views

Putting two wall-warts in series?

I'm helping a friend make a 48 inch hot-wire foam cutter. He would like it to be as economical as possible, so I'm giving him two 15V 1.1A wall wart power supplies that I have sitting around. I don't ...
10
votes
2answers
1k views

Is it safe to disassemble an unpowered PC power supply?

Once a typical PC power is unplugged, is there any danger of receiving a shock while disassembling it? Are there typically high voltages stored that one should be aware of? context: removing a ...
3
votes
2answers
205 views

How to properly isolate multiple power supplies

Say you have a single 110V AC supply and need to use it for a number of devices, each requiring very different characterists. For me personally these are: a direct use of the 110V AC supply for a ...
1
vote
1answer
136 views

relationship between temperture, current, thickness, and material

I used lan cable for light LED up on my bread board power source is PC's power supply. without any resistor, the lan cable melt! I reallize I have to keep OHM's law in my mind and use proper ...
3
votes
2answers
182 views

cable jacket melts

I am new to hardware. My breadboard just arrived and I am trying to light up my LED. I used computer power supply for power (red wire for + black for -) and used strands of LAN cable for connect LED ...
2
votes
3answers
941 views

Switching 120V AC with Digital Logic on Isolated Power Supply

Context: A digital phase-controlled light dimmer system. 120V AC mains I use an isolating transformer (and rectifying circuit) to generate +12V and +5V DC rails. I want to use reverse phase ...
6
votes
7answers
943 views

Is it safe to use a DC power adapter that isn't UL Listed or CSA certified?

I picked up a 9V switching DC adapter from SparkFun a while back, but I've been hesitant to use it because it doesn't have any of the usual "safety" approvals that you normally see on power adapters ...
9
votes
7answers
846 views

What if I overload a cheap AC adaptor?

I'm experimenting with PIC microcontrollers and various related circuits both on plugboards and simple homemade PCBS. I'd like to use various old AC power adaptors I have lying around to power my ...
5
votes
4answers
3k views

DIY Beginner's DC Power Supply?

My school uses HY 3005D-3 but I want to do it myself to save on $. Before opening it, I ask for tips about: not-to-break-it, cheap DC supply and DIY-materials (not that I know them soon). So how to ...