How to repair or design a 3005D Electronics Laboratory Variable Power Supply & formulas for 30V 5A

Showing all the secrets about its design. HY3005D or 305D is a common bench variable power supply on the workbench. With this video, students will get the basic knowledge for the first year of their schooling project.
Anybody electronics student will be able to start the homemade power supply project after this video.
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My gear Lab2:
- Siglent SDS1204X-E 200MHz Digital Storange Osclloscope Sponsored by SiglentEU dot com
- Siglent SDG2042X 120MHz Function/Arbitrary Generator Sponsored by SiglentEU dot com
- IEMI E-0208 120MHz Frequency Counter
- Uni-T UT71C 4000 Counts True RMS Multimeter Sponsored by Vitacom dot ro & Uni-T
- Uni-T UT502 Insulation Resistance Tester
- Fluke 8600A 4, 1/2 digit, Digital bench top Multimeter
- Newcason XC6013L Capacitance meter
- LCR-T4 component tester
- ZHAOXIN CD Power Supply TXN-1502D
- GORDAK 952 SMD Rework Soldering Station
- RadioShack 22-812 Digital Multimeter
- MIYAKO 890G Auto DMM
- DT-830B Multimeter
- TM902C Thermometer
- TDGC2A 0.5KVA Auto-transformer
- HS1010 Light Meter

My Gear Lab1
- ZOYI ZT102A Automatic Portable Digital Multimeter Sponsored By ZOTEK
- RIGOL DSO1051 50MHz Digital Storange Osclloscope
- FG-050 Low Frequency Function Generator 65.5KHz
- DATA PRECISION 2480R True RMS 4, 1/2 digits bench top multimeter 1
- DATA PRECISION 2480R True RMS 4, 1/2 digits bench top multimeter 2
- ZHAOXIN CD Power Supply TXN-1502D
- GORDAK 952 SMD Rework Soldering Station
- BRYMEN BM318 Automotive DMM
- STEREN PROAM MUL-280 Digital Multimeter
- LCR-T4 component tester

[andreiburak]

Good lesson! Thanks to the author! Only, I have a faulty pulse laboratory power supply element 3005D. It served me for seven years and suddenly broke. I would be glad and grateful to receive advice on its restoration.

[scottmorgan]

EXCELLENT teaching. We all need these kind of lessons to be better engineers. THANK YOU Sir for your fine work.

[albejanon]

Thanks for the explanations. A very good way to explain certain aspects of these power supplies. And thanks for make all the schematic tidy and clean, more easy to understand. Thanks.

[andrewverran]

Hi Bob, some of these power supplies have a current "on/off" push button between the current and voltage knobs, i think this is to avoid voltage spikes when the power supply is switched on while connected to a DUT.., Is this on/button a simple modification say on this power supply?
Much appreciated 😊

[airmailman]

Excellent video. Could you point me in the correct direction on a problem that i have with my power supply like this? When shorting the output of my 30V/3A unit, it goes into constant current mode but provides no voltage and current output no matter what the setting of the voltage or current knobs. I figure it's a setting but which one? I want to use this power supply to trace shorted components and it's useless for that if shuts down rather than provide a current.

[nathank]

Thanks so much for this video. Absolutely excellent. My power supply has 0V output. I’m trying to figure out what is the likely culprit. I think the reverse protection diode. Does that sound right? I found a zener diode that seems to 0V over it.

[abdulkhalegaliwan]

That's great thank you very very much

[leohobbleohobb]

Good video.Have Rnd KA320-KA3005D 30v 5 amp, same as Korad.Have blown current sense wire and the huge diode do to wrong polarity.1 time the current sence wire loose coiled 7 windings.How to make my own or get a replacement?.The diode is easy to get

[Влад_С]

Thanks, good video
guide for regulation this power unit exist?

[howardhall]

Great video, could clarify how you get the value of 4400 if at 25:51 I can, t seem to get the value from the formula, F is 50hz.? Many thanks.

[marko]

What is wrong if the power supply doesn't maintain a constant current on the resistive load? The current swings around 100 mA at 3A.

[harounsahnoun]

Got one with power issue, not going above 9 v on led display but shows 19 v on multimeter i replaced the 2n3770 Transistor but still same

[johnathan]

hi sir thank you for the video. can show me where to get all schematic circuit diagram. because i have 2 unit same like this but different model. and its all are SMD type. very difficult to troubleshooting without the circuit diagram.Thanks in advance

[braveheart]

Thanks sir for your job .... can you post the schematic.

[karlosarturo]

Gracias a mi tambien me interesa .sería bueno en castellano..ya q yo tengo una fuente similar..gracias por el vídeo
👍👍👍

[r-bp]

100 ohm resistors goes from 3055's emitters to opampN2 inverting input, they are not connected to 3055's base. There are BE-resistor (1k), which is connected from V20's base to emitter in 5 A model schematic. Your drawing at 23.12 three 100 ohm resistors are connected from base to the emitter, and missing 1k BE-resistor?

[elyas]

How we can increase Current 5A to 10A or more?

[ejpcellshop]

sir my sunshine DC POWER SUPPLY P-3005D, even without a load is allways full maximum apm on display and can't adjust with a potentiometer control what is the posible damage, thank you in advance

[josecarlosmonzon]

Podría explicarlo o traducirlo al castellano??, me parece muy interesante la publicacion.

[Dr.MagdyMourad-gb]

excellent but could you please explain it in a more detailed way ??