Experiments 1.2: Introductory Power Supply Circuit II (Mains PSUs)

This video continues from a previous video on setting up a simple battery power supply on a breadboard. This video uses a mains transformer 9V Power Supply Unit (PSU) that allows us to power circuits without the need of a battery. However, the supply is noisy and could lead to difficulties. A diode is added to protect the circuit from reverse connections. A switch is added to simplify usage. A PTC (Positive Temperature Coefficient) Transducer is added to protect the circuit from short connections and Capacitors are added to smooth the supply. We use the oscilloscope to examine the quality of the output supply.

Category:

Education

Tags:

• EE223
• Experiment
• Tutorial
• Digital Electronics
• LM7805
• KA7805A
• Diode
• Switch
• PTC
• Transducer
• Resettable Fuse
• Voltage Regulator
• LED
• Resistor
• Power Supply
• tutorial
• howto
• technology
• diy
• DCU
• Dublin City University
• Electronics
• Module
• Oscilloscope
• Signal Quality
• 1N4001
• diode
• Capacitor
• 0.1uF
• 100uF
• 10uF
• polarity
• Electrolytic Capacitor
• light
• robot
• instructions
• electronics
• commentary
• PSU
• Barrel Jack
• Rectifier Diode

[DerekMolloyDCU]

@EpicTronics Thanks for posting the update. I was thinking it could be that or that your PTC was under-rated - but in that case you should not have been getting an output.

[DerekMolloyDCU]

@CIPHERJAY It depends on the Voltage that you are running at and the current that it is drawing. At 12V with 300mA it would be P=VI = 3.6W, so I would go for the higher one. I can't remember which one I used, but it was probably one of their cheapest!

[ExtremHybrid]

Question: What PTC are you using? Manufacturer No. and details pls.

[DerekMolloyDCU]

@ExtremHybrid Good point. It is a Multicomp MC33175 (supplied by Farnell) 0.5A 90V DC Tripping Current of 1A. The other one I use is the MC33170 0.17A 60V DC Tripping Current of 0.34A. They have a full range and you can choose one depending on your PSU/Circuit requirements.

[ExtremHybrid]

PS.: In the end of the video you said "this module"....it would be great if you could sort ALL your videos into playlists and some how decide on a definitive, self-explanetory naming convention. (just my input). Keep it up!

[DerekMolloyDCU]

@ExtremHybrid Good idea - thanks for the input! I have updated all of the video titles to provide an ordering and I have added a playlist that identifies the main videos.

[dzxxbj]

@CIPHERJAY I think this part can be cannibalized from the old ones like radios etcs.You can find these easily .

[dquad]

Are EIA 3216 Capacitors directional?

[EpicTronics]

Actually, ignore my last post, I think I connected the PTC directly from the + pin on the switch and not the - pin !

[EpicTronics]

When I used my PTC, it became extremely hot. I am supplying 9v (from the plug socket). Would it be sufficient just to have the same circuit diagram as you have but without the PTC?

[garfrankwyn]

These are the best circuit building vids on the web, possibly the earth. I hope they pay teachers well in Dublin.

[CIPHERJAY]

@DerekMolloyDCU Thanks for the reply, the end part made me laugh!

[CIPHERJAY]

Hello again, im not sure what power rating i should have. From farnell there is a 2.7W or a 6.8W. What one would be best to power my circuits? Im using the same regulator that you have.

[CIPHERJAY]

Hello, would it be possible to give the full description of the barrel jack socket? I put a search into farnell however i cannot find the one you are using. Thankyou!!