I received the power supply in just a few days and in good shape. Like all good linear supplies, it is heavy because of the transformer. As advertised, it supplies clean power with very low noise - much lower than a comparable voltage/current switching supply. The case and display are very neat and functional. Because of some of the reviews, I was expecting the multifunction controls to be hard to learn, but after about 10 minutes, they all made sense and are easy to use. Although the instructions do not say so, you can enter a voltage or current and then get the least significant digit you want to use blinking. Then if you immediately start turning the control up or down, it will raise or lower the voltage or current smoothly while incrementing the higher order digits when you pass 9 or decrementing them when you pass 0. Thus, you do not necessarily need to set each digit individually as they describe. It also lets you search for a voltage or current that does what you are trying to do. All of the functions worked as advertised and are typical of quality lab power supplies. This power supply is not exactly cheap, but it is a fraction of the cost of most professional lab supplies. It is definitely worth the price.
There are only three negatives on the whole power supply, and one very small one was the banana plugs on the power leads. The springs were tight in the jacks, but the contact between the springs and the plug was intermittent. Whether this was poor construction or an attempt to allow the leads to swivel, it caused temporary interruptions of the current that would cause extreme problems in either analog or digital circuitry. I removed them and soldered on new plugs eliminating the problem. You should definitely examine the plugs. If the spring swivels easily on the plug, you should definitely replace them with better plugs. (Radio Shack sells banana plugs.)
The second negative is the very strong paint smell as it comes from the box. I finally put a light load on it and left it to run with the fan on for a day or so to finish curing the paint. This is not a long-term problem, but unexpected in a quality product like this.
The fan is very quiet under 1 amp, but jumps directly to high above 1 amp (at least with a 2 ohm load.) On high, the fan is pretty loud. A nice upgrade for the design would be a fan that is true variable speed based on heat sink temperature.
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Product Description
Our Heavy-Duty, Reliable, and Accurate vs. Copycats' Lightweight, Cheaply-constructed, and Poorly-performing, Your Choice
A linear power supply design applies the AC voltage to a power transformer to raise or lower the voltage before being applied to the regulator circuitry. Whereas a switch-mode power supply converts the AC power directly into a DC voltage without a transformer, and this DC voltage is then converted into a high frequency AC signal, which is used in the regulator circuit to produce the desired voltage and current. The linear power supply is quiet, stable, durable and heavy-duty with little noise, ripple, delay, and EMI, the switching type is just the opposite.
The Tekpower TP3005T variable DC power supply is a compact linear type instrument that is suitable for both Lab and industrial use. This digital DC power supply has maximum output voltage of up to 30 volts and current up to 5 amps. It comes with rotary switches for setting up the voltage and current. With its reliability and versatility, it's an invaluable and indispensable tool for testing, science project and etc., ideal for labs, research institutes, R & D facilities.
Specifications:
- Output DC Voltage: 0.0V – 30.0V
- Output DC Current: 0.00V – 5.00 A
- Input Voltage: 110V/AC, 60Hz
- Voltage and Current adjustment
- Voltage regulation: CV < 0.01% + 3mV, CC < 0.2% + 6 mA
- Load regulation: CV < 0.01% + 3mV, CC < 0.02% + 3mA
- Ripple and noises: CV < 1 mV rms, CC < 3 mA, rms
- Protection: High current limiting and cooling fan.
- Operating Temperature: 0 - 102 F (0 - 40 C), Relative Humidity: < 80%
- LCD Accuracy is within +/- 2.5%
- Size: 10 x 5 x 7 ¾ inches
- Weight: approx. 12 lbs
- TP3005T power supply
- Power cord
- Test leads with alligator clips (28 inches long)
- User manual
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Accurate and Versatile Linear Power Supply
Many reviewers stated their power supply had a strong odor when they unboxed it. In my case, I detected no odor, either when I first unboxed it or after operating it for a while.Some reviewers also commented on the loud heatsink fan noise when 1 amp or more was drawn from the unit. I tried to quantify the noise level using a sound-level meter located 2 feet in front of the supply and pointed at it. The results were: a. room ambient noise with the unit off - 62 dB. b. unit on and loaded to less than 1 amp - 63 dB. c. unit loaded with 1 amp or more - 65 dB.By comparison, the sound level of a hair dryer set to maximum speed was 70 dB at 2 feet from it. Yes, the increase in noise level of the power supply's fan is definitely noticeable when the load draws 1 amp or more but I didn't find it annoying. Apparently, the fan speed is triggered by the current output and not the heatsink temperature. The fan has only two speeds - low and high. It is always on at low speed until the load equals or exceeds 1 amp. There is a good YouTube tear-down review of the supply - search for eapbg #27. This video shows there is a heat sensor screwed to the heatsink. But this sensor appears to be used only to shut the power supply down if the heatsink temp exceeds a certain value, but I didn't attempt to verify this. The skimpy User's Manual only has the following two statements on the subject: "OVER HEAT PROTECTION: If the cooling fan fails to run, the system will detect it and stop working to protect the system." "INTELLIGENT HEAT RADIATION: The fan speed changes with the output power to lower the noise."I measured the unit's current draw from the 120 VAC line with no-load and with a 1 amp load: a. Idling with no load = 190 mA = 23 watts b. 1 amp load = 450 mA = 54 wattsBelow the AC power cord connector there is a 4-amp fuse. It required considerable force to pull out the slide-in fuse holder, which contains the active fuse as well as a spare - a nice touch.Using a couple of different multimeters, the accuracy of the voltage display was good out to 2 decimal places. For example, I set the voltage to 12.02 volts and that is exactly what my multimeters indicated both with no load and with a 1 amp load. This accuracy was observed across the entire voltage range. Current readings had similar accuracy.You set the voltage and current for your application by pushing in the respective knobs. You push a knob repeatedly until the display steps to the digit you want to set and it blinks. Then you have a few seconds to turn the knob to make your change. If you don't make a change during this time, the digit stops blinking and the display goes back to the original value. When you first turn on the supply, and press a knob, the left-most digit always blinks. However, if after the unit has been turned on and you have changed a digit, the next time you press the knob, the same digit you changed last will blink.The supply does have a memory feature that will save your last voltage and current settings when the unit is turned off and restore them when it is turned back onI examined the turn-on and turn-off characteristics of the output voltage by connecting an oscilloscope to the output and obtained the results shown in the attached photo. On the left is an on/off trace with the output set at 30 volts with no load. Note the 8 volt spike when the power supply was switched off. This spike disappeared at loads above 1 Kohm. Also, at voltages less than 30 volts, I saw no turn-off spikes with no load. For example, the trace on the right shows the no-load turn-off at 12 volts. The voltage ramp-up times were about 100 milliseconds at 30 volts and about 50 milliseconds at 12 volts with no turn-on spikes.I could detect no AC ripple on the output - it looked flat, except for approximately 40 mV of noise riding the output from extraneous RF sources that were picked up by my unshielded leads.There are a couple of minor design issues with the power supply. One is the lack of an output On/Off switch to remove voltage from the circuit being powered without having to use an external switch, disconnecting one of the output leads, or just turning the supply off. As a result, I intend to build a small switch box that will plug into the output terminals for use when testing breadboards.Another design issue is the lack of holes in the output banana jacks for secure attachment of wires without banana plugs. But one could still back off the plastic covers of the banana jacks, wrap the bare ends of wires around the shafts, then screw the covers back down to clamp the wires.Also the output banana jacks have a non-standard configuration. That is, the chassis ground jack is located between the negative and positive jacks. This arrangement would prevent the use of, for example, a standard dual banana plug-to-BNC adapter.I also discovered a minor problem with respect to the green CV (constant voltage) indicator LED. When the front panel was viewed from slightly above, the LED wasn't visible. But if viewed from a little below eye-level, the LED was visible. It appears the green LED was bent slightly upwards on the imternal circuit card and this prevented it from shining through the small hole in the plastic bezel. The other 3 LEDs are all red and much brighter than the green LED and were visible at any normal viewing angle.Other than those minor issues, I rather like this little supply. Frequent use will determine if it has an acceptable long-term reliability.
Top reviews from the United States
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Reviewed in the United States on January 7, 2016
Reviewed in the United States on June 23, 2018
Many reviewers stated their power supply had a strong odor when they unboxed it. In my case, I detected no odor, either when I first unboxed it or after operating it for a while.
Some reviewers also commented on the loud heatsink fan noise when 1 amp or more was drawn from the unit. I tried to quantify the noise level using a sound-level meter located 2 feet in front of the supply and pointed at it. The results were:
a. room ambient noise with the unit off - 62 dB.
b. unit on and loaded to less than 1 amp - 63 dB.
c. unit loaded with 1 amp or more - 65 dB.
By comparison, the sound level of a hair dryer set to maximum speed was 70 dB at 2 feet from it. Yes, the increase in noise level of the power supply's fan is definitely noticeable when the load draws 1 amp or more but I didn't find it annoying. Apparently, the fan speed is triggered by the current output and not the heatsink temperature. The fan has only two speeds - low and high. It is always on at low speed until the load equals or exceeds 1 amp. There is a good YouTube tear-down review of the supply - search for eapbg #27. This video shows there is a heat sensor screwed to the heatsink. But this sensor appears to be used only to shut the power supply down if the heatsink temp exceeds a certain value, but I didn't attempt to verify this. The skimpy User's Manual only has the following two statements on the subject:
"OVER HEAT PROTECTION: If the cooling fan fails to run, the
system will detect it and stop working to protect the system."
"INTELLIGENT HEAT RADIATION: The fan speed changes with
the output power to lower the noise."
I measured the unit's current draw from the 120 VAC line with no-load and with a 1 amp load:
a. Idling with no load = 190 mA = 23 watts
b. 1 amp load = 450 mA = 54 watts
Below the AC power cord connector there is a 4-amp fuse. It required considerable force to pull out the slide-in fuse holder, which contains the active fuse as well as a spare - a nice touch.
Using a couple of different multimeters, the accuracy of the voltage display was good out to 2 decimal places. For example, I set the voltage to 12.02 volts and that is exactly what my multimeters indicated both with no load and with a 1 amp load. This accuracy was observed across the entire voltage range. Current readings had similar accuracy.
You set the voltage and current for your application by pushing in the respective knobs. You push a knob repeatedly until the display steps to the digit you want to set and it blinks. Then you have a few seconds to turn the knob to make your change. If you don't make a change during this time, the digit stops blinking and the display goes back to the original value. When you first turn on the supply, and press a knob, the left-most digit always blinks. However, if after the unit has been turned on and you have changed a digit, the next time you press the knob, the same digit you changed last will blink.
The supply does have a memory feature that will save your last voltage and current settings when the unit is turned off and restore them when it is turned back on
I examined the turn-on and turn-off characteristics of the output voltage by connecting an oscilloscope to the output and obtained the results shown in the attached photo. On the left is an on/off trace with the output set at 30 volts with no load. Note the 8 volt spike when the power supply was switched off. This spike disappeared at loads above 1 Kohm. Also, at voltages less than 30 volts, I saw no turn-off spikes with no load. For example, the trace on the right shows the no-load turn-off at 12 volts. The voltage ramp-up times were about 100 milliseconds at 30 volts and about 50 milliseconds at 12 volts with no turn-on spikes.
I could detect no AC ripple on the output - it looked flat, except for approximately 40 mV of noise riding the output from extraneous RF sources that were picked up by my unshielded leads.
There are a couple of minor design issues with the power supply. One is the lack of an output On/Off switch to remove voltage from the circuit being powered without having to use an external switch, disconnecting one of the output leads, or just turning the supply off. As a result, I intend to build a small switch box that will plug into the output terminals for use when testing breadboards.
Another design issue is the lack of holes in the output banana jacks for secure attachment of wires without banana plugs. But one could still back off the plastic covers of the banana jacks, wrap the bare ends of wires around the shafts, then screw the covers back down to clamp the wires.
Also the output banana jacks have a non-standard configuration. That is, the chassis ground jack is located between the negative and positive jacks. This arrangement would prevent the use of, for example, a standard dual banana plug-to-BNC adapter.
I also discovered a minor problem with respect to the green CV (constant voltage) indicator LED. When the front panel was viewed from slightly above, the LED wasn't visible. But if viewed from a little below eye-level, the LED was visible. It appears the green LED was bent slightly upwards on the imternal circuit card and this prevented it from shining through the small hole in the plastic bezel. The other 3 LEDs are all red and much brighter than the green LED and were visible at any normal viewing angle.
Other than those minor issues, I rather like this little supply. Frequent use will determine if it has an acceptable long-term reliability.
Some reviewers also commented on the loud heatsink fan noise when 1 amp or more was drawn from the unit. I tried to quantify the noise level using a sound-level meter located 2 feet in front of the supply and pointed at it. The results were:
a. room ambient noise with the unit off - 62 dB.
b. unit on and loaded to less than 1 amp - 63 dB.
c. unit loaded with 1 amp or more - 65 dB.
By comparison, the sound level of a hair dryer set to maximum speed was 70 dB at 2 feet from it. Yes, the increase in noise level of the power supply's fan is definitely noticeable when the load draws 1 amp or more but I didn't find it annoying. Apparently, the fan speed is triggered by the current output and not the heatsink temperature. The fan has only two speeds - low and high. It is always on at low speed until the load equals or exceeds 1 amp. There is a good YouTube tear-down review of the supply - search for eapbg #27. This video shows there is a heat sensor screwed to the heatsink. But this sensor appears to be used only to shut the power supply down if the heatsink temp exceeds a certain value, but I didn't attempt to verify this. The skimpy User's Manual only has the following two statements on the subject:
"OVER HEAT PROTECTION: If the cooling fan fails to run, the
system will detect it and stop working to protect the system."
"INTELLIGENT HEAT RADIATION: The fan speed changes with
the output power to lower the noise."
I measured the unit's current draw from the 120 VAC line with no-load and with a 1 amp load:
a. Idling with no load = 190 mA = 23 watts
b. 1 amp load = 450 mA = 54 watts
Below the AC power cord connector there is a 4-amp fuse. It required considerable force to pull out the slide-in fuse holder, which contains the active fuse as well as a spare - a nice touch.
Using a couple of different multimeters, the accuracy of the voltage display was good out to 2 decimal places. For example, I set the voltage to 12.02 volts and that is exactly what my multimeters indicated both with no load and with a 1 amp load. This accuracy was observed across the entire voltage range. Current readings had similar accuracy.
You set the voltage and current for your application by pushing in the respective knobs. You push a knob repeatedly until the display steps to the digit you want to set and it blinks. Then you have a few seconds to turn the knob to make your change. If you don't make a change during this time, the digit stops blinking and the display goes back to the original value. When you first turn on the supply, and press a knob, the left-most digit always blinks. However, if after the unit has been turned on and you have changed a digit, the next time you press the knob, the same digit you changed last will blink.
The supply does have a memory feature that will save your last voltage and current settings when the unit is turned off and restore them when it is turned back on
I examined the turn-on and turn-off characteristics of the output voltage by connecting an oscilloscope to the output and obtained the results shown in the attached photo. On the left is an on/off trace with the output set at 30 volts with no load. Note the 8 volt spike when the power supply was switched off. This spike disappeared at loads above 1 Kohm. Also, at voltages less than 30 volts, I saw no turn-off spikes with no load. For example, the trace on the right shows the no-load turn-off at 12 volts. The voltage ramp-up times were about 100 milliseconds at 30 volts and about 50 milliseconds at 12 volts with no turn-on spikes.
I could detect no AC ripple on the output - it looked flat, except for approximately 40 mV of noise riding the output from extraneous RF sources that were picked up by my unshielded leads.
There are a couple of minor design issues with the power supply. One is the lack of an output On/Off switch to remove voltage from the circuit being powered without having to use an external switch, disconnecting one of the output leads, or just turning the supply off. As a result, I intend to build a small switch box that will plug into the output terminals for use when testing breadboards.
Another design issue is the lack of holes in the output banana jacks for secure attachment of wires without banana plugs. But one could still back off the plastic covers of the banana jacks, wrap the bare ends of wires around the shafts, then screw the covers back down to clamp the wires.
Also the output banana jacks have a non-standard configuration. That is, the chassis ground jack is located between the negative and positive jacks. This arrangement would prevent the use of, for example, a standard dual banana plug-to-BNC adapter.
I also discovered a minor problem with respect to the green CV (constant voltage) indicator LED. When the front panel was viewed from slightly above, the LED wasn't visible. But if viewed from a little below eye-level, the LED was visible. It appears the green LED was bent slightly upwards on the imternal circuit card and this prevented it from shining through the small hole in the plastic bezel. The other 3 LEDs are all red and much brighter than the green LED and were visible at any normal viewing angle.
Other than those minor issues, I rather like this little supply. Frequent use will determine if it has an acceptable long-term reliability.
Images in this review
Top reviews from other countries
K
Adjusting the voltage may destroy your device if your not super careful.
Reviewed in Canada on November 18, 2023
