February 05, 2010

Newly added: Programmable DC power supply with USB


We have added a new model of programmable DC power supply, model HY3005DP.

The output of this highly stable, high quality DC power supply is continuously adjustable at 0-32V DC and 0-5A.

With its full digital control and 5 memory settings, it's extremely easy set up the output you want and repeat the settings you use regularly.

What's more, you can use the USB interface and software that comes with the unit to program a waveform, essentially use this power supply as a simple arbitrary waveform generator.

The unit comes with very bright LED displays, providing accurate readout for the voltage and current values. This unit has toggle switch at the back that allows you to operate it in 110V AC or 220V AC.

Check out HY3005DP here:

 programmable DC power supply HY3005DP

February 04, 2010

New Switching Power Supplies with over-voltage protection

We are pleased to announce the arrival of EX models, a new line of switching power supplies that have built-in over-voltage protection, over-current protection, and over-temperature protection. The EX models are best suited for the following applications:


  • battery charging for Lithium Polymer (LiPo), Lithium Ion, Lithium Manganese, A123 (LiFePO4), NiCd, NiMH, Lead Acid batteries (Flooded, Gel, AGM, SLA), etc.

  • as electroplating and anodizing rectifiers

  • electrolysis, hydrogen generator, fuel cell applications, etc.

  • DC motors, slot cars, aviation applications, etc.

with the over-voltage protection, you no longer need to worry about reverse EMF feeding back into the Mastech power supplies and damaging the power supplies. You can even accidentally hook up the battery with the wrong polarity, and the power supplies will be fine. If you turn off the power supply while the DC motoring is running, that's fine too. In a nutshell, much more robust and much more versatile.

 We also added HY3080EX, and HY30100EX, capable of outputting up to 80A and 100A respectively, excellent for applications that require large current like anodizing, electro-plating, and hydrogen generators.

 Go to Mastech Switching Power Supplies

June 10, 2009

Mastech Power Supply Forum up and running


Finally we re-installed the forum for Mastech Power Supply again, after we had to shut down last time due to spammers. We apologize for the inconvenience, and hope to use the forum as tool to answer all technical questions. Please visit us at to post any technical questions and get answers from our knowledgeable staff and expert users around the world.

Sean from

June 03, 2009

How to Set Current Limit for Mastech CC CV Power Supply?

Setting the current limit for Mastech power supplies is a little bit more complicated compared to setting the voltage limit, especially if you have one of the following situations:

1) your load has internal source of EMF, this includes battery, DC motors, RC cars and trains, any electrochemical systems including plating, etching, and electrolysis, etc.

2) your load might be sensitive or damaged by over voltage, e.g., LED

In the first scenario, you need to make sure to set the voltage to slightly above the maximum EMF from your load, say 0.8V to 1.5V above, and set the current to minimum before connecting the load. Once you connect the load, you can slowly increase the current limit by adjusting the current knob to the desired value. It is highly advised to have a diode put in line with your load (connecting to the positive terminal of the power supply) to prevent the current flowing in the wrong direction and causing damage to the power supply.

In the second scenario, if you can find a simple load like a power resistor or a halogen lamp that can handle the current you want to pass, you can set the current similar to the first scenario (Caution: the power resistor or lamp might be very hot if you are passing large current). Once you are done with setting the current limit, turn the voltage down to minimum, disconnect your load of resistor or lamp, then connect you actual load. you can now slowly increase the voltage while leaving the current setting, just remember to always stop before you raise the voltage too high for your load. If your calculation is correct, then you should be able to stop the voltage knob before actually damaging your load.

If you cannot find a power resistor or lamp, you can still set the current limit you want by following the steps below:

Step 1: before connecting your load, set the voltage limit to safely below what's allowed by your load, and set the current to minimum. The power supply should be in "CV" mode.

Step 2: Connect the load; the Mastech power supply should be in "CC" mode. Slowly increase the current limit, if you are lucky, you can reach the desired current limit before you need to do anything.

Step 3: If you cannot reach the desired current before the power supply switched over from "CC" to "CV", turn the current slightly down so the power supply is switched back to "CC". When in "CC" mode, you can turn the current knob down a little bit more to have a feel about how much turn corresponds to what current change. Using this gut feel, increase the current knob so that it is half way between your desired current level and the maximum you can get without increasing the voltage setting, now the power supply should be in "CV" mode. You can now increase the voltage knob a little, still making sure that it's below what's safely allowed for your load, and stop when the power supply switches from "CV" to "CC". Now you can see what the actual current is. If the current is higher than your desired value, reduce the current setting to your desired value and you are done. If it's lower than what you desire, repeat Step 3 until you get desired current setting.

It sounds complicated, but when you are actually doing it, it only
takes minutes to set it.

 Go to Mastech Power Supply Home

April 18, 2009

What is CC and CV Mode of a CC CV Power Supply?

A Mastech Power Supply is a CC CV power supply can be operated in either of the two modes: CC (constant current) and CV (constant voltage) mode. You can tell which mode the power supply is in by looking at the front panel, where either the "CC" or "CV" indicator light is on. Needless to say, if "CV" light is on, it means that the power supply is in constant voltage mode.

If you are a novice user, you may wonder what does it mean? With any Mastech power supply, you can set both the current and voltage using the knobs in the front. By doing so, you are not setting the actual current or voltage, you are merely setting the limits for voltage and current.

If you remember Ohm's Law, you know that at any given load, you can only control either the current or the voltage, the other is determined by Ohm's Law and the load. When the "CV" light is on, it means that the voltage you see on the display (which is always the actual voltage the power supply is putting out) is the same as the voltage you set, while the current you set is higher than the actual current allowed in the particular configuration. This is because with the particular load connected, you have reached the limit set by the voltage knob. Alternatively, when the "CC" light is on, the current on the display (which always shows the actual current flowing through the circuit) is the same as the current limit you set, and the voltage limit you set is higher than the actual voltage displayed on the power supply.

April 12, 2009

New power supplies available

We have recently added the following power supplies to our inventory:

Mastech Linear variable DC Power Supply HY3010D

Mastech Linear regulated power supply HY3020D

Mastech Linear regulated power supply HY5005D-2


With these addition, we have not only dramatically increase the choices of linear power supplies, especially the higher current power supplies. HY6020E, with up to 60V in output voltage and 20A in output current, is one of the most powerful power supplies we carry so far.