wow - i wish I had come across your videos sooner. You have a knack of bringing complex theoretical aspects to a very simple level. Please keep these coming.
I can't believe I actually got to grips the mathematics as you explained each step, especially how you chose the components and the reasons behind it. Thank you so much for making this video.
nice basic circuit. can use power MOS FET with some changes . FET is voltage controlled. also IGBT can be used. can use the PNP 2N2905A and tip42C just flip circuit around. current flows in PNP in outher direction.
I know the 2N3055 is the default transistor for circuit explanation designs, but some alternatives I've seen are the TIP147c, 2SC4706, 2SD1047, MN2488. They all have slight differences between specs but should be able to work in some circuits. Sometimes it seems like the 2N3055 is overpriced specifically because they are sought out by people that haven't figured out how to find and use equivalent or near equivalent devices. I know the TL081 based adjustable bench power supply kits sold for around $5 use a 2SD1047 as the main power transistor. IIRC that kit is based on an Elektor magazine article from the 70's (or 80's). The design originally specified a 2N3055 ;) Thanks for this upload Lewis. I was actually following a 'plate circuit' on your website yesterday and was trying to figure out why I was having trouble with overheating a collector resistor on a switched lighting circuit. I should have realised the circuit is already current limited by the load when using the low side switch. You reached through my phone for that facepalm moment when you mentioned here that the motor limits the current in the circuit you described. Thanks again. -Jake
Thanks. could you tell me where is the problem? i used arduino input (Blink example) to the base of tip120 with rb=1000kohm, trying to switch a load with 3.1 ohm, Vmax=1.4, and imax=1.14 amps. whatever i changed the Rc, Vdc, i couldn't get the desired current or voltage to drive the load. the second issue is, when measuring the load voltage using a multimeter, it does not turn off !
Hi Mr. Lewis, Thank you very much for the info of using the optocoupler to drive 2n3055, can you replace ignition coil 12vdc in place of a motor and please can you give me the voltage input minimum and maximum of the optocoupler how many bolts was in your recent video, thanks, Romeo jr.
I would replace the 2N3055 with a higher voltage rated transistor such as the BU508 or BUP941 because of the high induced voltages that exist in the ignition coil driver circuit when switching the coil off. There is a disadvantage with the first transistor suggested because it has a low Hfe figure below 5 meaning it has to be driven with fair amount of current from the rest of the driver circuit to work properly.
The motor should have a diode protection circuit when the 2n3055 switches OFF inductance in the motor will cause stored energy in the electro-mechanical motor to be generate a huge voltage spike that will easily exceed 60Vce, destroying the entire circuit It is common to connect a large diode across inductive loads to prevent such voltage spikes .
@@LewisLoflin Hi Lewis, I'm a bit confused. At 5:00 minutes into the video, based on the base current requirements, we require 500mA to ensure the 2N3055 has a collector current of 10A. If we use a 47 ohm resistor and based on I2R dissipation, it amounts to about 11.5W (0.5^2*47) of power dissipated from that base resistor. Shouldnt we be using a higher powered resistor? Thanks
I'm interested in your discussion, but the constant interruptions by ads wanting to sell me something is just too much to bare. Do you really need all this commercialization to promote your website?
I'm giving this a lot of thought. I tried donations in the past, zero. Many of the ads are too many and often crap unrelated to the video. Worse I'm censored on certain subjects due to Google politics. Even worse they ran ads to other related websites on my channel. Any ideas? I'm coming to the point of pulling most ads.
@@LewisLoflin no, you didn’t. Anyway it’s always good to be patient and do the math. Actually the tolerance of the resistor gave me less than 500mA - 400mA. But 15W will be safe.
wow - i wish I had come across your videos sooner. You have a knack of bringing complex theoretical aspects to a very simple level. Please keep these coming.
I can't believe I actually got to grips the mathematics as you explained each step, especially how you chose the components and the reasons behind it. Thank you so much for making this video.
Haven't seen this channel in a long time. Excellent channel too, I learnt a lot from here👍😊🇮🇪
Welcome!
nice basic circuit. can use power MOS FET with some changes . FET is voltage controlled. also IGBT can be used. can use the PNP 2N2905A and tip42C just flip circuit around. current flows in PNP in outher direction.
Loved the vídeo. A nice and useful solid state relay. Thanks a lot !
Hervorragender Beitrag
I know the 2N3055 is the default transistor for circuit explanation designs, but some alternatives I've seen are the TIP147c, 2SC4706, 2SD1047, MN2488. They all have slight differences between specs but should be able to work in some circuits.
Sometimes it seems like the 2N3055 is overpriced specifically because they are sought out by people that haven't figured out how to find and use equivalent or near equivalent devices.
I know the TL081 based adjustable bench power supply kits sold for around $5 use a 2SD1047 as the main power transistor. IIRC that kit is based on an Elektor magazine article from the 70's (or 80's). The design originally specified a 2N3055 ;)
Thanks for this upload Lewis. I was actually following a 'plate circuit' on your website yesterday and was trying to figure out why I was having trouble with overheating a collector resistor on a switched lighting circuit. I should have realised the circuit is already current limited by the load when using the low side switch. You reached through my phone for that facepalm moment when you mentioned here that the motor limits the current in the circuit you described.
Thanks again.
-Jake
I agree but in general the same rules apply in the design.
Thanks. could you tell me where is the problem? i used arduino input (Blink example) to the base of tip120 with rb=1000kohm, trying to switch a load with 3.1 ohm, Vmax=1.4, and imax=1.14 amps. whatever i changed the Rc, Vdc, i couldn't get the desired current or voltage to drive the load. the second issue is, when measuring the load voltage using a multimeter, it does not turn off !
Smart man. Very well spoken. Thank you.
Excelente video!!! Saludos desde Guayaquil-Ecuador
Best explanation ever, thanks
Hi Mr. Lewis,
Thank you very much for the info of using the optocoupler to drive 2n3055, can you replace ignition coil 12vdc in place of a motor and please can you give me the voltage input minimum and maximum of the optocoupler how many bolts was in your recent video, thanks,
Romeo jr.
I would replace the 2N3055 with a higher voltage rated transistor such as the BU508 or BUP941 because of the high induced voltages that exist in the ignition coil driver circuit when switching the coil off. There is a disadvantage with the first transistor suggested because it has a low Hfe figure below 5 meaning it has to be driven with fair amount of current from the rest of the driver circuit to work properly.
Thank you very much for explanation every part 😊
The motor should have a diode protection circuit
when the 2n3055 switches OFF inductance in the motor will cause stored energy in the electro-mechanical motor to
be generate a huge voltage spike that will easily exceed 60Vce, destroying the entire circuit
It is common to connect a large diode across inductive loads to prevent such voltage spikes .
OK.
PC817 (optocoupler) was originally made by SHARP. Now, it is made by others, as well.
Superb explanations.
How many Watts the 47-ohm resistor should be? Nice and very useful video!
1 watt to be safe.
@@LewisLoflin Hi Lewis, I'm a bit confused. At 5:00 minutes into the video, based on the base current requirements, we require 500mA to ensure the 2N3055 has a collector current of 10A.
If we use a 47 ohm resistor and based on I2R dissipation, it amounts to about 11.5W (0.5^2*47) of power dissipated from that base resistor.
Shouldnt we be using a higher powered resistor?
Thanks
Yes use a 15 watt.
@@NikonCrayzee Use an N-Channel Mosfet instead of 2N3055, it's a much simpler circuit.
@@charleslyell3748 but did you notice, that this tutorial is about using a BJT not a MOSFET?
What's an "h bridge"?
An H-bridge is usually four transistors or switches arranged to forward-reverse a DC motor.
Thank you Sir for this informative video.
I'm interested in your discussion, but the constant interruptions by ads wanting to sell me something is just too much to bare. Do you really need all this commercialization to promote your website?
I'm giving this a lot of thought. I tried donations in the past, zero. Many of the ads are too many and often crap unrelated to the video. Worse I'm censored on certain subjects due to Google politics. Even worse they ran ads to other related websites on my channel. Any ideas? I'm coming to the point of pulling most ads.
Thank you for another usefull video.
Useful video
Ok, just make some maths before burning the 47 ohm resistor - this must be 8 Watts at least!!! The voltage drop is about 20V and 500 mA of current.
I don't think I gave the wattage. I believe it is 12 watts. 20 X 0.5 = 12.
@@LewisLoflin no, you didn’t. Anyway it’s always good to be patient and do the math. Actually the tolerance of the resistor gave me less than 500mA - 400mA. But 15W will be safe.
@@JurekPrzezdziecki Thanks for noting this. I need to put the wattage into the next video.
@@LewisLoflin BTW, what kind of dc motor do you have in mind? for CNC?
🌿