Post by Honus on Nov 30, 2015 7:34:39 GMT
If you're doing electronics work sooner or later you will need some way to power your project during testing. There are lots of different ways you can accomplish this-
1) Wall wart or power brick. You probably have several of these just sitting around. Typically these are low current switching power supplies. On the back of the casing the manufacturer usually states the input/output voltage and current capacity. The vast majority of wall warts are unregulated, meaning the output voltage listed on the case is really just a guideline for what the output will be when a load is attached. For the most part these are fairly worthless and I'd probably avoid using them. Some wall warts are regulated- usually the USB variety in the form of cell phone chargers are pretty reliable at putting out 5V at a few hundred milliamps and these are decent for powering something like an arduino.
If you have something like a laptop power brick or a printer power supply you can make it much more useful by running its output through an adjustable breadboard power supply- www.adafruit.com/products/184
With this little board you can connect a wall wart or power brick and get a regulated 3.3V, 5V or adjustable power output. You're limited by the current capacity (1.25A max) so it's fine for powering an arduino or small servos. You could also use something like a 5V 7805 voltage regulator in order to get a clean regulated 5V from a higher output non regulated wall wart.
2) Batteries. It's a pretty simple matter to connect some batteries together (or buy a battery pack) to obtain the proper voltage you need. Batteries provide nice clean power and the combination of a battery pack with a regulator can provide you with just about any needed voltage. For high current applications avoid using alkaline cells- go for NiMH, NiCD or Lithium chemistry batteries instead.
With a battery pack powering high current draw servos and a breadboard power supply powering your microcontroller and/or soundboard you can get by pretty well for very little money. It's not terribly convenient but it definitely works.
3) PC power supply. These switching power supplies are great for powering larger motors because they can deliver a lot of current for very little money. There are a few companies (notably Sparkfun and Dangerous Prototypes) that make breakout boards for turning these into bench power supplies. With an ATX power supply you get 3.3V, 5V, 12V and 12V output. You will have to add additional circuitry in order to get adjustable voltage or current limiting. A quick google search will turn up countless tutorials for making a DIY bench power supply from an ATX power supply.
4) Lab bench power supplies. This is probably the best/most versatile solution and of course tends to be the most expensive. There are two options- new or used. Used power supplies can be purchased on eBay for reasonable money and I'd probably stick to the better quality linear power supplies like Power Designs, Lambda or HP/Agilent. Most of these power supplies are very robust and have a very long lifespan. I'd probably go for one that has at least 7V/3A output with adjustable current/current limiting. The high end precision power supplies are nice but it's really not necessary- if you need a precision power supply then you probably know all about them. Typically with a used bench power supply the things to look for are leaky capacitors and corrosion, especially on switch and pot contacts. Both of these are usually easy to fix with minimal time and effort. One thing I really like about the older power supplies is the use of analog meters. Digital readout is great for voltage but an analog panel meter is really nice for viewing current spikes, such as when a servo first starts to move.
With new power supplies the sky is the limit. If you're on a budget I'd check out Circuit Specialists as they seem to have a pretty good reputation. You can everything from single output linear models to triple output models. Some of these will have a single fixed 5V output and an adjustable output, which is pretty handy and costs around $150. If you've got money to burn and you like nice test gear then get one of the newer Rigol programmable units. The Rigol DP832 programmable linear power supply has three outputs (30V, 30V and 5V) rated at 3 Amps each and will probably do everything you ever wanted for about $450.
1) Wall wart or power brick. You probably have several of these just sitting around. Typically these are low current switching power supplies. On the back of the casing the manufacturer usually states the input/output voltage and current capacity. The vast majority of wall warts are unregulated, meaning the output voltage listed on the case is really just a guideline for what the output will be when a load is attached. For the most part these are fairly worthless and I'd probably avoid using them. Some wall warts are regulated- usually the USB variety in the form of cell phone chargers are pretty reliable at putting out 5V at a few hundred milliamps and these are decent for powering something like an arduino.
If you have something like a laptop power brick or a printer power supply you can make it much more useful by running its output through an adjustable breadboard power supply- www.adafruit.com/products/184
With this little board you can connect a wall wart or power brick and get a regulated 3.3V, 5V or adjustable power output. You're limited by the current capacity (1.25A max) so it's fine for powering an arduino or small servos. You could also use something like a 5V 7805 voltage regulator in order to get a clean regulated 5V from a higher output non regulated wall wart.
2) Batteries. It's a pretty simple matter to connect some batteries together (or buy a battery pack) to obtain the proper voltage you need. Batteries provide nice clean power and the combination of a battery pack with a regulator can provide you with just about any needed voltage. For high current applications avoid using alkaline cells- go for NiMH, NiCD or Lithium chemistry batteries instead.
With a battery pack powering high current draw servos and a breadboard power supply powering your microcontroller and/or soundboard you can get by pretty well for very little money. It's not terribly convenient but it definitely works.
3) PC power supply. These switching power supplies are great for powering larger motors because they can deliver a lot of current for very little money. There are a few companies (notably Sparkfun and Dangerous Prototypes) that make breakout boards for turning these into bench power supplies. With an ATX power supply you get 3.3V, 5V, 12V and 12V output. You will have to add additional circuitry in order to get adjustable voltage or current limiting. A quick google search will turn up countless tutorials for making a DIY bench power supply from an ATX power supply.
4) Lab bench power supplies. This is probably the best/most versatile solution and of course tends to be the most expensive. There are two options- new or used. Used power supplies can be purchased on eBay for reasonable money and I'd probably stick to the better quality linear power supplies like Power Designs, Lambda or HP/Agilent. Most of these power supplies are very robust and have a very long lifespan. I'd probably go for one that has at least 7V/3A output with adjustable current/current limiting. The high end precision power supplies are nice but it's really not necessary- if you need a precision power supply then you probably know all about them. Typically with a used bench power supply the things to look for are leaky capacitors and corrosion, especially on switch and pot contacts. Both of these are usually easy to fix with minimal time and effort. One thing I really like about the older power supplies is the use of analog meters. Digital readout is great for voltage but an analog panel meter is really nice for viewing current spikes, such as when a servo first starts to move.
With new power supplies the sky is the limit. If you're on a budget I'd check out Circuit Specialists as they seem to have a pretty good reputation. You can everything from single output linear models to triple output models. Some of these will have a single fixed 5V output and an adjustable output, which is pretty handy and costs around $150. If you've got money to burn and you like nice test gear then get one of the newer Rigol programmable units. The Rigol DP832 programmable linear power supply has three outputs (30V, 30V and 5V) rated at 3 Amps each and will probably do everything you ever wanted for about $450.
