Tekpower TP3005T Variable Linear DC Power Supply

[MarkF]

Looking for a sub $100 power supply.  Does anyone have this Tekpower TP3005T or seen a review?

[Electro Fan]

The TP3005T looks pretty good.  FWIW, I have a Tekpower TP1503C (15 Volts, 3Amps, analog meters, CC and CV) that sells for about half the price of the TP3005T.  I like it and use it occasionally but I also have a Korad KA3005P which I like and use much more often.  The Korad will cost somewhat more than the TP3005T but for me it's worth it due to a few features.  1) In addition to a rotary knob for changing values it has a couple arrow keys that I think might speed up the setting process over how the TP3005T works (this is just a guess since I haven't used the TP3005T.  2) It has a DC output on/off button (to me, this is a very useful feature, others might not care.)  3) The memory buttons are also useful. 4) It has a USB port for PC control. Korad makes a similar model KA3005D that doesn't have the USB port.

http://www.amazon.com/KORAD-KA3005D-Precision-Adjustable-Regulated/dp/B0084JFWNY/ref=sr_1_3?ie=UTF8&qid=1437109319&sr=8-3&keywords=korad

But for about $7 more the USB port on the KA3005P is probably an ok investment.  Based on how the Tekpower TP1503C operates I think the TP3005T might be a fine unit if you can't justify the extra $ for one of the 3005 Korads.

[dmmt40]

I've actually purchased this supply just a couple of days ago, but won't be receiving it until next week. I'm going to take a look inside to check quality, safety, etc if you want I can post some pictures.

I think it came out just 1 or 2 months ago that's why there's little info about it.

[Electro Fan]

I've actually purchased this supply just a couple of days ago, but won't be receiving it until next week. I'm going to take a look inside to check quality, safety, etc if you want I can post some pictures.

I think it came out just 1 or 2 months ago that's why there's little info about it.

dmmt40, Welcome to the EEVblog forum!  Please let us know your impressions of the TP3005T.   EF

[dadler]

Is this the same supply rebranded?

http://www.circuitspecialists.com/csi3005t.html

[MarkF]

I've actually purchased this supply just a couple of days ago, but won't be receiving it until next week. I'm going to take a look inside to check quality, safety, etc if you want I can post some pictures.

I think it came out just 1 or 2 months ago that's why there's little info about it.

I don't have an immediate need, so pictures would be great.  If you do any testing, I would be interested if there's any large overshoot when the power is turned on and what the ripple and noise is like.  Also, how it is to operate.     
Thanks.

[Electro Fan]

This is from a Tekpower TP1503C Power Supply.

Different model than the one you are interested but it's a less expensive version (15V, 3A, analog meters).

Images show turn on and turn off from main AC switch.  Also an image showing the Voltage set to about 2-3 mVolts (my Fluke 179 fluctuated between 2-3 mV while trying to very delicately set the power supply voltage knob).

Not too bad for a $39.99 Power Supply.

[tautech]

Also an image showing the Voltage set to about 2-3 mVolts (my Fluke 179 fluctuated between 2-3 mV while trying to very delicately set the power supply voltage knob).

And one while under a moderate load, say 1A @ 12V AND AC coupling?

[Electro Fan]

Also an image showing the Voltage set to about 2-3 mVolts (my Fluke 179 fluctuated between 2-3 mV while trying to very delicately set the power supply voltage knob).

And one while under a moderate load, say 1A @ 12V AND AC coupling?

I'll give a try (it's getting late here). 

One other note, I think my scope reads about 4-8% high on voltage when measuring in the 0-10 Volts range.  I've come to think that scopes in general don't measure voltage as well as DMMs but maybe it's just my gear or technique.

[tautech]

Also an image showing the Voltage set to about 2-3 mVolts (my Fluke 179 fluctuated between 2-3 mV while trying to very delicately set the power supply voltage knob).

And one while under a moderate load, say 1A @ 12V AND AC coupling?

I'll give a try (it's getting late here). 

One other note, I think my scope reads about 4-8% high on voltage when measuring in the 0-10 Volts range.  I've come to think that scopes in general don't measure voltage as well as DMMs but maybe it's just my gear or technique.

Without a load on the supply, quite likely.
Other than high end scopes are rarely very accurate, for AC and DC within capability of your DMM, trust it.

[Electro Fan]

Also an image showing the Voltage set to about 2-3 mVolts (my Fluke 179 fluctuated between 2-3 mV while trying to very delicately set the power supply voltage knob).

And one while under a moderate load, say 1A @ 12V AND AC coupling?

I'll give a try (it's getting late here). 

One other note, I think my scope reads about 4-8% high on voltage when measuring in the 0-10 Volts range.  I've come to think that scopes in general don't measure voltage as well as DMMs but maybe it's just my gear or technique.

Without a load on the supply, quite likely.
Other than high end scopes are rarely very accurate, for AC and DC within capability of your DMM, trust it.

Do you want the channel AC coupled, or the trigger AC coupled, or both AC coupled?

[tautech]

Channel AC coupled only.

[Electro Fan]

Channel AC coupled only.

Best I could round up (so as to keep my resistor from getting too hot) was a 10 Ohm, 10 Watt, 10% resistor - so I set the Power Supply for 5 Volts and drew about 0.5 Amp as confirmed by a couple multimeters.

Channel AC coupled only On and Off, followed by other variants for your viewing delight.

[Electro Fan]

Channel AC coupled only.

tautech,

I've previously just looked at the DC coupled waveforms (looking for overshoot and noise).  What is your diagnosis of the AC channel coupled images?  Are those what you expected or were you looking for something else?  Thx, EF

[dmmt40]

Is this the same supply rebranded?

http://www.circuitspecialists.com/csi3005t.html

Yep, I think so.

[dmmt40]

I don't have an immediate need, so pictures would be great.  If you do any testing, I would be interested if there's any large overshoot when the power is turned on and what the ripple and noise is like.  Also, how it is to operate.     
Thanks.

No problem I will do some tests on it.

Electro Fan
Those are some good pictures, it seems like a good PSU for the price, the only thing missing though (and I think what tautech was suggesting) is to look at the ripple under load with AC coupling, should be easy now that you have everything setup.

[tautech]

Channel AC coupled only.

tautech,

I've previously just looked at the DC coupled waveforms (looking for overshoot and noise).  What is your diagnosis of the AC channel coupled images?  Are those what you expected or were you looking for something else?  Thx, EF

I was hoping for a shot of ripple under a moderate load. Could be any load, I suggested ~1A and 12V thinking you might have maybe an auto light bulb or similar.
AC coupling is to exclude the DC and channel attenuator needs to be set right down low in the mV ranges. With a Linear supply, ripple will most likely be at mains frequency, so the Timebase should be set for that but have a look for any HF stuff too.
Reasonable specs will be under 5mV ripple, good under 2mV.

Those are some good pictures, it seems like a good PSU for the price, the only thing missing though (and I think what tautech was suggesting) is to look at the ripple under load with AC coupling, should be easy now that you have everything setup.

Exactly. 

[Electro Fan]

Not sure if this is what you guys are looking for.  I left the 10 Ohm, 10 Watt resistor in place with the PS set to 5 Volts DC output.  This is drawing 0.5 Amps.  I set the scope for 50 mV and 50 ms for one and 50 mV and 10ms for the other.  ... Added one more at 50 mV and 5 ms.  The long spikes might correspond to the 60 Hz AC cycle?  Let me know if you want me to try something different.

[Electro Fan]

Here is another at 20 mV and 1 us.  What is interesting about this is that the Power Supply was OFF; but the two DMMs were still connected and turned on.  I'm going to run another to see what happens when I remove the DMMs.

[tautech]

Not sure if this is what you guys are looking for.

We're looking for PSU ripple. This is how PSU quality/design is judged.

Yep, that sort of stuff, but your trigger level is above the waveform and trigger set tor +&- triggering not just rising. Set probe and channel input to 1:1.

It's also likely some of the garbage is from your surrounds/workplace.
Turn on some averaging to clean things up a little.

Thanks for your trouble. 

Here is another at 20 mV and 1 us.  What is interesting about this is that the Power Supply was OFF; but the two DMMs were still connected and turned on.  I'm going to run another to see what happens when I remove the DMMs.

Yea, it tricky trying to do stuff that others want to see, especially when in a hurry and you don't do that stuff frequently.

[Electro Fan]

I'm happy to keep trying.  Here is one with the DMM's completely out of the testbed.

[tautech]

I'm happy to keep trying.

Disconnect DMM, attach load to PSU, probe at PSU terminals.
PSU ON

Aquire menu, set to averaging, let's say 64.
Have a play around, there's no hurry.

[Electro Fan]

Ok, learning something here.  I have a noisy environment.

All of the following is done with AC channel coupling.

Turns out that about smallest increment I can discern with just the Rigol scope turned on is about 250-500 microVolts.  That is, with nothing plugged in and the channel on the signal displayed on the screen with it's attendant noise is about 250-500 microVolts.  When I plug in a Tektronix BNC cable (about 30" long) nothing changes on the scope signal - it is still approaching 500 microVolts.  When I add a BNC to banana plug connector (so the banana plugs can plug into the Power Supply) the signal jumps to a range of 2.5 milliVolts to 5 milliVolts depending on the orientation of the cable with the connector (it seems to act as an antenna).

When I plug the BNC cable from the scope through the BNC to banana plug connector into the Power Supply (with the Power Supply OFF and it's AC cord disconnected from the PS), the signal settles down to show about 2.5 milliVolts at it's "core" but the nose emanating from the top and bottom of the "core" of the signal takes the signal to about 7.5 milliVolts peak to peak.  Plugging the AC cord into the wall and into the PS doesn't have any impact on the signal amplitude.

When I turn the PS on to 5 Volts (with no load), the signal rises to 5 Volts and looks clean but when I zoom in by setting the scope to 5 mV it becomes apparent that the signal has a "core" component that is about 2.5 mV and the noise takes the overall signal to about 7.5 mV peak to peak - this is with no load.

When I turn the PS off, attach the load to the PS, and attach the scope to the PS I get a signal of about 8.3 mV peak to peak.  When I turn the PS on, I get the image below which shows what I refer to as the "core" of the signal being about a third of the overall signal which measures with the cursors as being about 9 mV peak to peak.

How much of the 9 mV is due to the PS and how much is noise from cables, connectors, or all of the above acting as an antenna I don't know but after working my way through this I am thinking that some of it is noise from the environment.  I have found that depending on how I orient cables and connectors and how I hold them can have a dramatic impact (10x?) on the noise level.

So, my assessment so far is that the Tekpower TP1503C has relatively little overshoot on turn on and turn off (see the earlier images posted) and it might be about 3 mV for ripple.  I can't say for sure given my adhoc technique and what I think is a noisy setup and/or environment. 

Over thoughts:  I like having a PS with analog meters but I wouldn't want it to be my only PS.  If I only had one PS there is no doubt it would be worth the extra $ to have digital readouts for Volts and Amps, but all in all if someone needs a PS for $40 the Tekpower TP1503C seems like a reasonable starter unit (but I'd still hold out for digital readouts if you can). 

[Electro Fan]

I'm happy to keep trying.

Disconnect DMM, attach load to PSU, probe at PSU terminals.
PSU ON

Aquire menu, set to averaging, let's say 64.
Have a play around, there's no hurry.

I tried averaging at 64.  Using averaging with Stop yields about the same results as reported above (about 9 mV peak to peak).  Using averaging while in Run shows a peak to peak of about 2 mV - 4 mV depending on how you interpret the display (minus a few outlier spikes it's 2 mV, taking into consideration a few spikes across the display it's 4 mV).

- Thanks for the guidance

[tautech]

That result is fine and a good indication that ripple is reasonably low.

Averaging can be useful in noisy environments.

You shoud be able to do screen captures without having to Stop the scope.
Got a Print or Save button or similar?
You might have to change settings to get it to print/save to USB.