Mastech is an established brand in variable DC power supplies with over 20 years of experience in making high quality DC power supplies. Mastech power supplies are widely used by the engineering, scientific, and hobbyist community. Mastech manufactures a wide selection of DC power supplies ranging from 18V and 3A (maximum power of 18X3=54W) to 30V and 50A (Max power 1500W). Below we will cover some of the key considerations for deciding if and which Mastech Power Supply will meet your potential needs.
Mastech Power Supply Characteristics
The model number of Mastech power supply says a lot about what kind of power supply it is, take for example HY3005D-3, the first two letter HY has no specific meaning other than indicating it’s a Mastech power supply; the first two digits “30″ indicates the maximum voltage it can put out, i.e., 30V; the next two digits “05″ is the maximum current it can put out in each output channel, in this case 5A; the letter “D” indicates that this is linear power supply (which we will cover later); the next “-3″ indicates that it’s a triple outputs power supply, meaning you can get three independent outputs, typically with 2 adjustable and the third one fixed at 5V. Likewise HY5020E means it’s a single output power supply with 50V maximum voltage output and 20A maximum current output, and it’s a switching power supply.
Mastech power supplies typically come with displays for both voltage and current, which always shows the actual output, not the setting you input. This is potentially confusion for some novice users, e.g., if you have a power supply turned on with no load connected, when adjusting the voltage setting (say to 15.0V), you will see the meter displays exactly what you set at 15.0V, but if you adjust the current setting to say 2.0A, you will see it actually stays at 0.0A. This is normal because the output is limited by either the voltage or current setting, and determined by the law of physics. In this case because there is no load connected, we have an open circuit, so no current can flow, and the current is at 0.0A, while the voltage is at the amount limited by the setting of 15.0V.You also will see the “CV” light on indicating that the power supply is acting as a constant voltage source. Let’s say now you connect an 1 Ohm resistor between the + and – terminals, with the same setting, you will see the voltage drops to 2.0V and the current increases to 2.0A. In this case the current flows through the system and is now limited by the setting of 2.0A, and the voltage setting of 15.0V is higher than what Ohm’s Law dictates (which is 2.0V). You will also see the “CC” light on indicating now the power supply behaves as a constant current source. Only by increasing the current setting can the output voltage be increased at this point until the current reaches 15.0A.
Mastech power supplies are great for almost any applications that require DC powers, including circuit design and testing, DC motors, hobby works like clocks, radios, RC cars and trains, electrochemical works like electrolysis and plating, battery charging, etc., for example, Mastech DC power supplies are great for fast charging A123 batteries due to their price and power rating.
There are two designs for the Mastech power supplies: linear and switching. The traditional linear power supplies are typically heavy, durable, and have low noise across low and high frequencies. For this reason they are mostly suitable for lower power applications where the weight does not pose a problem. The switching power supplies are much lighter, more efficient, durable, and have some high frequency noise due to the design. For this reason, the switching power supplies are not suitable for high frequency audio applications but are great for high power applications. Other than that, these two types are pretty much swappable for various applications, and they cost about the same to make. We have seen another eBay guide saying that the switching power supplies are not suitable for plating or ionization, it is misleading and not true. A user does need to take some precautionary measures to protect the power supplies at high power applications and we will provide specific instructions when shipping our power supplies.
Choosing the right model
The key consideration is to figure out what is the maximum voltage and maximum current you need for your application. Typically there is no need to pick a model that has higher rating than your maximum voltage and current, except in the case of high power application, where we recommend you to go up one notch in current rating, e.g., if your application requires maximum of 30V and 5A, the model HY3010E should be sufficient; on the other hand, if your application requires output of 28V and 20A for a long time, it might be a good idea to get the model HY3030E instead. Other things to consider include the type of displays (LCD or LED), single or multiple outputs, etc. The industry trend is to move away from LCD displays to LED displays, as bright LED displays are now widely available at comparable cost. Color LED displays are also available from Mastech with models like 3005F-3 and 3003F-3. If you do a lot of circuit design and testing, triple output supplies are a plus as they provide two adjustable outputs plus a third output at 5V fixed; the two adjustable outputs can be operated at independent, series or parallel mode, providing a very wide range of voltage and current.