So i just got my first power supply (Dr. Meter 30v 5a). I've finished doing the basic circuits in my arduino kit, and i have a small supply of parts (pots, resistors, capacitors, bread boards) from hobby lasers, like LM317s. I don't have any 555 timers, and am trying to figure out what are good cheap (preferably free at this point) projects to get better at understanding circuits. I live in the boonies so anything new has to be ordered.

I like magnetic field stuff (motors, solenoids, etc.), but I do have a pile of LEDs, and a few Laser diodes.
I would really like to know how to make my own oscillators, inverters, and transformers.

 

If you have an Arduino then it sounds like you want to learn some embedded stuff. Start with the basics: light a led, read a switch, read the voltage on a pot (does the Arduino do that? I don't use them). Then maybe get an alphanumeric display to show something.

You can have some fun with that and learn the basics for more advanced projects.

 

So i just got my first power supply (Dr. Meter 30v 5a). I've finished doing the basic circuits in my arduino kit, and i have a small supply of parts (pots, resistors, capacitors, bread boards) from hobby lasers, like LM317s. I don't have any 555 timers, and am trying to figure out what are good cheap (preferably free at this point) projects to get better at understanding circuits. I live in the boonies so anything new has to be ordered.

I like magnetic field stuff (motors, solenoids, etc.), but I do have a pile of LEDs, and a few Laser diodes.
I would really like to know how to make my own oscillators, inverters, and transformers.

That power supply, is it 0 to 30v ? If not it would probably fry all the components you have listed, if you don't regulate it down.

 

gerty - its a HY3005D variable with single output. it has those two dials (4 total) for fine and coarse current and voltage.

ErnieM - the led and pot sounds like a good idea to start. My arduino kit came with stuff related to a serial monitor and ways of reading voltage, etc. You can do almost anything with an arduino (uno), as long as its between 3 and 5 volts and low amps, but it makes it so easy to succeed that I wasn't learning much and when something failed I was lost. I did learn that not all diagrams are correct and sometimes diodes are pictured backwards.

 

If you haven't already, make an LED "throb". It's a great little project with visual feedback. I found a nice result sending it PWM with the duty cycle following a sine wave. Then you can send it other profiles, for instance you could simulate a flickering candle with the same technique. Then learn how to use external transistors, relays and trials to scale up the power.

What you do depends on what catches your fancy. Some people like audio, so they build guitar amps or headphone amps. Some like radio, so they make an FM transmitter. Many like LEDs, changing colors and brightness on command. Then there's the world of interfacing to the world with sensors for temperature, light, sound, weight, pressure, acceleration and on and on. Of course there are robotics projects. If you want to involve your computer, play with bluetooth and wifi modules.

There's really no limit except your own initiative. Just look around on MAKE and you'll see what a lot of other folks are doing.

 

Wayneh - With arduino i made an LED throb, even did the Knight Rider effect, but that's the chips and the program doing all the heavy lifting. I actually have no idea how to do that with diodes, capacitors, and resistors.

I turned on the power supply today and ran an incandescent at about 26mA 1.5v and a Cree LED at 30-100mA and 2.6v-3.7v. So far I learned I do not fully understand how the power supply works. It seems like the voltage is set by the LED, and then the Amperage dials are automatically switched on, while the voltage is locked.

 

A power supply always has to figure out which mode of control to apply. For instance if I tell it to not supply over 100mA, I can only control voltage below that current level. If I try to exceed it, the supply goes into current-control and holds fast to 100mA. Or if I set the max voltage to 12V, I can vary current all I want as long as it doesn't require more than 12V to hit the target. When it does, the constant voltage control will take over and stop me from exceeding 12V no matter how much current I ask for.

It can seem a bit confusing at first, so keep playing with the light bulbs. You'll get a feel for it.

 

A lot of newbies do not understand how to use a power supply or even how to apply Ohm's Law.

The HY3005D is a CC/CV (constant current/constant voltage) power supply.
You can set it for constant current OR constant voltage. NOT both at the same time.
Ohm's Law must apply.
For a fixed resistance, voltage and current are proportional, i.e, increase the voltage and the current will increase (until you reach the current limit).

Think of CONSTANT to mean LIMIT.

Constant current is the current limit. The supply will not exceed this current setting.

Constant voltage is the voltage limit. The supply will not exceed this voltage limit.

How to set the current limit

Set the COURSE Voltage and Current settings to mid range.
Get a piece of cable and SHORT the power supply, i.e. connect the +ve (RED) and -ve (BLACK) terminals.
Don't be afraid to do this. A properly functioning bench power supply is designed to withstand a short circuit. If it fails then it is junk.
The current readout should be high. The voltage readout should be close to zero.
Adjust the Current setting to whatever max limit you desire, e.g. 200mA.
Remove the short. The current readout should be zero.
Set the voltage to whatever you desire, e.g. 5V.
Your power supply is now set up as constant voltage of 5V with a limit of 200mA.

Go find a 12V bulb from an old junk car. Connect it to the power supply and play with it at different current and voltages.
Try different voltage settings from 0V to 14V. Readout the current and voltage and calculate the wattage consumed by the bulb.
Plot the current vs voltage.
Plot the wattage vs voltage.
Plot the resistance vs voltage.