Adjustable Power Supply- amps or volts?

[GunsOfNavarone]

I"d like to get a bench power supply and I'm a bit lost on this option, Volt or amps? That is, if you had the option of 120v but only 3 amps OR 30v bot 10amps, which would you find more desirable. I;m sure the follow up question, "what are you using it for"? As I am starting to build more electrical things in the CNC world, I have been in situations that I wish I had one. No one will be flamed for giving me an answer I find not ideal for me a year down the road.
Honestly, I'm leaning 30v 10 amps for whatever that's worth.
As always, thank guys for your input!

 

[Ulma Doctor]

most things cnc will work from either 24v or 5v signal respectively.

i use variacs and inexpensive regulated power supplies for bench testing
and would use regulated power supplies when dealing with anything CNC

like these...

12V 24V - 2A to 30A Amp Switching Power Supply Adapter for LED Strip | eBay

DC 12V 30A Size 215 115 50mm With Internal Fan. DC 24V 2A Size 110 78 36mm. DC 24V 10A Size 198 110 50mm With Internal Fan. DC 24V 15A Size 215 115 50mm With Internal Fan. DC 24V 20A Size 225 125 50mm With Internal Fan.

www.ebay.com

the price is low, so i keep a few on hand

 

[GunsOfNavarone]

Thanks doc. I'm actually looking at the ones with digial readout for both volt/amps. Apple to apples I guess but more idiot proof when your not paying attention, not to mention overload protection and such. Those I don't believe, can you adjust volts/amps independently.

 

[Ken from ontario]

I have seen 5 amps China made variacs dirt cheap but the vreviews are mostly good:

Amazon.com: YaeCCC Auto Voltage Transformer AC Variable Voltage Converter Transformer 110VAC Input, 0-130VAC (500W): Industrial & Scientific

Buy YaeCCC Auto Voltage Transformer AC Variable Voltage Converter Transformer 110VAC Input, 0-130VAC (500W): Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[GunsOfNavarone]

Would those VarI Acs be any good for anodizing? (Different subject)

 

[ahazi]

Doc, what brand is the variac? I have seen 5 amps China made variacs dirt cheap but the vreviews are mostly good:

Amazon.com: YaeCCC Auto Voltage Transformer AC Variable Voltage Converter Transformer 110VAC Input, 0-130VAC (500W): Industrial & Scientific

Buy YaeCCC Auto Voltage Transformer AC Variable Voltage Converter Transformer 110VAC Input, 0-130VAC (500W): Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

For variable AC output get the biggest variac (2,000 watt) the price difference is small and it is useful to have more capability. I have one like this on my bench.

For a bench use, a DC variable power supply with proper protection etc I use this model. It is very hefty (30 volt, 5 amp) and the price is very good.
https://www.amazon.com/gp/product/B00ZBCLJSY There are other DC power supplies that "look the same" but they are a cheaper switching (light weight, no transformer), without a linear regulators and are more noisy and not reliable. The one above is very good and built well. I designed and built many power supplies over the years, I know the difference...

Glad to help with electronics as I am a relatively novice machinist but electronics is what I am doing for almost 50 years.

Ariel

 

[MSBriggs]

Most electronic devices need a specific DC voltage, and draw up to a certain current (amps). So you select a power supply that supplies that voltage, with a current rating of the required amps or higher. If you are using a variable power supply, you have to be sure to set the voltage at the designated level so as not to damage item that you are powering. Many adjustable supplies also have fixed voltage outputs of common values (5 V, 12 V, ...). Some have "crowbars", where for safety you can prevent the supply from exceeding an adjustable maximum voltage, so as to protect whatever you are powering. I prefer adjustable DC power supplies that have both voltage and current controls. In typical operation where you want a particular voltage, you set the current setting high so that it is not controlling, and adjust the voltage to the desired value. For electrolysis rust removal, I prefer to operate in current limiting mode, at much lower amps and voltage than it seems most people are using.

 

[SLK001]

I"d like to get a bench power supply and I'm a bit lost on this option, Volt or amps?

This mostly depends on what you are going to use the power supply for. Do you want a linear supply or a switching supply? Your 30V @ 10A supply, if linear, would be quite heavy (300 WATTS). A switching supply is generally a noisy supply - a lot of voltage "hash" on the output, while a linear supply is generally very clean. A lot of circuits that require 30A can get by with a switching supply. Circuits that require 12V @ 1A usually require a more stable and cleaner supply.

If you're beginning to experiment with electronics, then a clean, linear 30V @ 2A supply is an overall good pick. These supplies usually have both CV and CC controls (constant voltage and constant current). There are versions out there that are dual 30V @ 2A supplies, which means that there are two independent supplies neatly contained in one box. I think that you want a dual 30V @ 2A supply, with CV and CC controls.

 

[Ken from ontario]

Would those VarI Acs be any good for anodizing? (Different subject)

That's a good question, I don't know anything about anodizing but wouldn't mind to know the answer.

For variable AC output get the biggest variac (2,000 watt) the price difference is small and it is useful to have more capability. I have one like this on my bench.

I mainly want to use it for a 3 AMPS, 230 Watts ,brushed motor, I would consider the bigger variac if I could set the output not to go beyond 3 AMPS.

 

[markba633csi]

You might find you need both: A variac for variable ac and a dc bench supply with volt and current meters/adjustments.
If you do electrical stuff enough you will find uses for one of each (or more!)
-Mark