tag:blogger.com,1999:blog-401164737462963207.post6279391607970258960..comments2024-03-18T03:57:53.839-07:00Comments on Ben Krasnow: How to design a transistor circuit that controls low-power devices (tutorial)Ben Krasnowhttp://www.blogger.com/profile/04234629396863486242noreply@blogger.comBlogger44125tag:blogger.com,1999:blog-401164737462963207.post-4072960099178419072014-10-30T23:55:23.666-07:002014-10-30T23:55:23.666-07:00Anonymous, it's important to have such a resis...Anonymous, it's important to have such a resistor for insulated-gate transistors where the gate impedance is very high (eg MOSFETs) and may not be properly driven during microcontroller startup (for example). For bipolar transistors, the base impedance is very low once above the PN forward voltage. Adding a resistor wouldn't really accomplish much.Ben Krasnowhttps://www.blogger.com/profile/04234629396863486242noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-70907118885583282372014-10-30T05:02:47.360-07:002014-10-30T05:02:47.360-07:00Thanks Ben, very interesting, I just would like if...Thanks Ben, very interesting, I just would like if you added there a base-emitter parallel resistor (high value) since transistors must not be used with open base.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-84039436748875782802014-04-11T11:32:35.007-07:002014-04-11T11:32:35.007-07:00hey ben plz tell me why diode used in a tip120 dar...hey ben plz tell me why diode used in a tip120 darlington transistor circuitsonal sinhahttp://facebook.com/sonal.sinha2noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-67790644391068709612012-10-31T12:29:57.956-07:002012-10-31T12:29:57.956-07:00Hi Ben, what about a direct projection into eye, u...Hi Ben, what about a direct projection into eye, using a small projector from outside the eye? It could be done in such a way that the project get corrected to fit the eye geometry.... <br /><br />Maybe projection is more suitable and plausible...<br />I can´t think how to create such a small projection, its a challenge.. what do you think about that?Pablo Carneiro Eliashttps://www.blogger.com/profile/05972276363328518436noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-6097640577759721822012-10-30T21:52:48.174-07:002012-10-30T21:52:48.174-07:00Anonymous, you should check the specific transisto...Anonymous, you should check the specific transistor's datasheet. For example, the Fairchild PN2222A shows an hFE of minimum 100 when the collector current is 150mA. This would imply a base current of appx. 1.5mA. When the collector current is 500mA, hFE is only 40, which would imply a base current of appx 12mA.<br /><br />hFE depends on a few variables -- notably temperature and collector current, so check the datasheet and looks for hFE graphs for your specific part. I've never heard of "force gain". Ben Krasnowhttps://www.blogger.com/profile/04234629396863486242noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-50067920692265303722012-10-30T15:21:19.356-07:002012-10-30T15:21:19.356-07:00Hai Ben,
Very nice explanation! This thread: http...Hai Ben,<br /><br />Very nice explanation! This thread: http://forum.allaboutcircuits.com/showthread.php?t=9751 got me a bit confused, though. Let me quote the relevant part: "hFE is used to bias a linear amplifier transistor, not a saturated transistor. It has plenty of collector to emitter voltage when it is a linear amplifier. It has a very low collector to emitter voltage when it is saturated.". According to the same author, you would need to use the "force gain" instead of hFE, which never seems to be more than a factor 10 - 25 or so. Now I wonder if I should use 10 (force gain) or 100+ (hFE) in the calculations.<br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-87606587974475275492012-04-17T21:41:05.915-07:002012-04-17T21:41:05.915-07:00RvA, it's just an estimated value. I believe i...RvA, it's just an estimated value. I believe it mostly serves to slow down the rise-time of the inductive kick so that the diode has time to start conducting. The voltage rating is more critical than the capacitance value since it must be able to control fast-rising voltages from the inductive load.Ben Krasnowhttps://www.blogger.com/profile/04234629396863486242noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-87215818700110434442012-04-17T01:49:51.323-07:002012-04-17T01:49:51.323-07:00Hi Ben. Very well explained.
Just a question, I w...Hi Ben. Very well explained. <br />Just a question, I would like to see how You did calculate the capacitor value and needed voltage value? Now it look like 'wet finger work' or a general known value. I guess that when it value is too big that the relay or coil get activated for a short moment when the capacitor get filled.<br />Thank you very much.RvAnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-25132726847248610192012-04-07T18:20:52.531-07:002012-04-07T18:20:52.531-07:00thanks Mr.Ben for your kind replay.this is very he...thanks Mr.Ben for your kind replay.this is very helpful for me.sreehttps://www.blogger.com/profile/02739172466166880230noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-56460614081857596622012-04-07T11:52:27.715-07:002012-04-07T11:52:27.715-07:00sree, your question is go general, I really cannot...sree, your question is go general, I really cannot give you an answer in these comments. Capacitors store electrical charge and are used to perform many functions in electronic circuits. I would suggest a book on introductory electronics and AC circuit theory.Ben Krasnowhttps://www.blogger.com/profile/04234629396863486242noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-89070025917913451072012-04-07T01:04:04.871-07:002012-04-07T01:04:04.871-07:00this is a great video ! thanks !. i have a doubt t...this is a great video ! thanks !. i have a doubt that, what is the use of capacitors in electronic circuit and how can we easily find the value of capacitor we need ?. pls help me , i want to design a power amplifier then how the capacitor value will be calculated ?sreehttps://www.blogger.com/profile/02739172466166880230noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-58156228124190144682011-12-15T21:14:01.215-08:002011-12-15T21:14:01.215-08:00A really good video on how to design a basic circu...A really good video on how to design a basic circuit and the points to take into consideration.. Thanks a lot..Uttamnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-19618348131196312002011-11-18T08:23:53.127-08:002011-11-18T08:23:53.127-08:00Hi Been I would like to know if u have and more v...Hi Been I would like to know if u have and more videos like this.Very Educational. -JerryAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-45213660780871771032011-08-12T14:23:58.490-07:002011-08-12T14:23:58.490-07:00Anonymous, your requirements will very likely requ...Anonymous, your requirements will very likely require more than just one transistor for each solenoid. If I were building the circuit, I would be tempted to use a microcontroller with on-board ADC. These can be had for less than $5, and would allow fine-tuning of the setpoints, turn-off behavior, hysteresis, separate indicator LEDs, etc, etc. The whole circuit would only require one microcontroller, potentiometer, and three output transistors. Take a look at the Atmel ATtiny13 or ATtiny26.Ben Krasnowhttps://www.blogger.com/profile/04234629396863486242noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-34941049768466880362011-08-11T12:10:48.733-07:002011-08-11T12:10:48.733-07:00Ben, I enjoyed your video as I am trying to figure...Ben, I enjoyed your video as I am trying to figure out how to make a similar circuit. <br />I would like to use 3 solenoids on a 12v dc system using 0-5 volt rheostat. The 1st solenoid needs to turn on around 1.5v, the 2nd at around 3v ( while turning off the 1st one), then the 3rd at 4.5v (while turning off the first 2). Assuming the same solenoid values as yours, how do I do this?<br /><br />Thanks<br />RobAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-61144662267136669542011-06-10T14:27:42.645-07:002011-06-10T14:27:42.645-07:00Leo, the air valve is made by Clippard. http://ww...Leo, the air valve is made by Clippard. http://www.clippard.com/ The website is a little difficult, so you may want to request a print catalog. There is a helpful chart at the beginning of the electronic valves section that shows flow rate for all of Clippard's models. The one in my video is a manifold-mount 3-way "mouse valve"Ben Krasnowhttps://www.blogger.com/profile/04234629396863486242noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-35893194762925048312011-06-10T09:51:57.043-07:002011-06-10T09:51:57.043-07:00Hi Ben,
I am interested in the Air Valve you used...Hi Ben,<br /><br />I am interested in the Air Valve you used. I need to source something like that for an motorcycle project that I have on the go. Can you give me more information on it?<br /><br />Thanks,<br /><br />LeoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-80547810828859335022011-06-09T13:53:18.165-07:002011-06-09T13:53:18.165-07:00Hey Ben
I updated my blog profile, please email m...Hey Ben<br /><br />I updated my blog profile, please email me.<br />Thanks!,<br />SteveReformerhttps://www.blogger.com/profile/11860914540880093167noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-20592691331655750582011-06-07T20:37:27.416-07:002011-06-07T20:37:27.416-07:00Ben I've been using PN2222A for a long time on...Ben I've been using PN2222A for a long time on this kind of projects. However, I surely learned at least a couple of new things today thanks to your explanation. Thank you, great video.Rodhttps://www.blogger.com/profile/01741754287652489213noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-17057867438688520522011-06-07T15:09:44.026-07:002011-06-07T15:09:44.026-07:00This comment has been removed by the author.Rodhttps://www.blogger.com/profile/01741754287652489213noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-6574135779007837892011-06-07T11:14:29.728-07:002011-06-07T11:14:29.728-07:00Hi,
great Job!
What is the book in the backgroun...Hi,<br /><br />great Job!<br /><br />What is the book in the background?<br /><br />Thanks,<br />AndyAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-60672225042975250932011-06-07T09:54:16.630-07:002011-06-07T09:54:16.630-07:00Thanks for the great tutorial, I've learned a ...Thanks for the great tutorial, I've learned a lot! I also like the fact that you speak so clearly and slowly.<br /><br />Cheers from Hungary!Lászlóhttps://www.blogger.com/profile/17588305644375543248noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-47247607064363027712011-06-07T07:34:38.533-07:002011-06-07T07:34:38.533-07:00Ben,
Thanks so much for posting this, I learned a...Ben,<br /><br />Thanks so much for posting this, I learned a few things. Do you have an email address, I might have a project you'd be interested in.<br /><br />Thanks again<br />SteveReformerhttps://www.blogger.com/profile/11860914540880093167noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-35114155708162733182011-06-07T05:42:46.583-07:002011-06-07T05:42:46.583-07:00Why is it so simple when explained with a good lit...Why is it so simple when explained with a good little video. Hope I had back in college.<br />Thanks, that's a good explanation that cleared some points in my mind :)pmercierhttps://www.blogger.com/profile/15075220192854577923noreply@blogger.comtag:blogger.com,1999:blog-401164737462963207.post-38191226405959430982011-06-07T02:49:56.979-07:002011-06-07T02:49:56.979-07:00This is a Great tut ! (notice the upper "G&qu...This is a Great tut ! (notice the upper "G"). You just go through theory, answering a lot of basics concepts that newbies can't find find easily on the Internet.<br />Thank you.Anonymousnoreply@blogger.com