Will just have to find an Equivalent Transistor and all should be good. It work fine with led but it didn't work when i replace a dc motor for led.my dc motor even work with 1.5v voltage.what can i do? If the supply is rated at minimum 6V, then a 5V/6V relay can be tried, however this will demand relatively high current from the cells and can deplete it quickly. The alarm gives 145 dB and will scream for hours! Is it possible to have the LCD screen trigger the circuit, switch on the el wire device and then turn off after 1 minute of inactivity? It just uses two power transistors, two resistors, and one transformer only. It goes off when anyone touches the clock, but at the moment it is locking on after the touch. after interrupting the supply. It indicates the alarm has been triggered. If you keep the NPN base permanently connected to the supply then the LED will stay always ON. I need to pick your brains for a little project I am trying to put together for my kids. R2, C2 will need to be experimented to get the required delay, and since 1 sec is very less, you can replace D1 with a short link….you can even eliminate the relay if you are able to configure the PNP transistor’s collector with your lamps. The application, just put relay instead of LED. Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. I will post a link to my project, once I have it completed.Thanks for any assistance. please try increasing the 1K resistors to 10K and see the response 🙂. HI, I’m new to electronics but have played around with 12v relays and LEDS for various projects for awhile. The circuit can run off a voltage of 9 – 12 dc volts. All the designs are fully adjustable. Here are many interesting sites about these. The explained circuit can be used for all applications which calls for an initial delay ON feature for the connected load after the mains power is switched ON. (We need to creat a ON time dealy). You can also check if your SSR connections are correctly implemented, the (-) should connect with the ground, and the (+) should connect with the collector of the PNP transistor. Dennis, any SSR will require just a few mA to switch, which should not cause any loading on the driver circuit unless the supply current is too low, or the SSR itself is faulty. ... Sound Generator (26) Oscillator circuits (22) 555 Timer (22) Basic Electronics (62) … Connect its collector/emitter across R1. I am sending by email a schematic of my circuit. In the first circuit, you can remove the 1000uF capacitor and replace the push switch points with a 100uF capacitor, now it'll behave in the way you have suggested, you may need to tweak the value of the 33k resistor in order to achieve the required 1 sec timing. and then would shut off and not reset. The LEd and its resistor will also need to be removed and replaced with a relay, as shown in this example article: https://homemade-circuits.com/2014/06/input-trigger-synchronized-monostable.html. Hi,I need a circuit which has two out on and off.I mean one on and the other off and reverse with transistor or mosfet.So i can pulse it with 555.Thanks. Thanks in advance! Is is possible to make a circuit that lights up a bulb but then a momentary switch can cut the power to turn the led light off? HI, Do you have a variation on this circuit so that after you release the switch, the circuit remains dead for about 5 minutes and then allows the switch to be pushed again? Regards Dave. the base resistor of the BC557 could require an increase to may be upto 100k, Thank you so much for the article! The delay period may be set by appropriately selecting the values of R2 and C2. Can anyone please let me know what needs to be done to the pcb to fix my issue. I would like the solenoid to activate when power is applied (no trigger button) and stay on for at most 10 seconds (6-10 seconds set via RC would be okay). 🙂 But I still don't understand why with the relay connected I cannot increase the timing resistor beyond 40k ohms? This is like popping the clutch on a manual transmission car, anyway my car reacts to quickly and the result is a redlight, leaving to early,  and you lose the race. You can use it for the mentioned purpose. The problem with my circuit is if you block the LDR the alarm goes silent and it doesn’t shut off after 1 minute. Also connect a 10K across the base/emitter of the BC547. There is a light which has two functions: one is to illuminate the rear number (licence) plate and the other is to illuminate the boot when the boot lid is raised and the general car lighting is off. They use IC-4017 to drive LEDs and IC-555 as an oscillator pulse generator. But I need the transistor to provide power to the alarm UNTIL it is turned on, then it needs to CUT power to the alarm for a fraction of a second to reset it. Only when I turn off the switch the relay gets off immediately,there is no 5 sec delay even then. The control input is acquired from the alarm output as indicated in the above description. The KD9561 alarm stops and the LED stays lit, which is correct. Thank you. Thank you. The solenoid would then deactivate, even though power is still applied, until power is removed and then reapplied. Nice work! The 4 diode idea would effectively work for a delay ON timer, but since here we are discussing a delay OFF timer, the idea would be disadvantageous. Then it would require the manual reset switch to restore the circuit back to its normal state where its waiting on S2 to open. I am a bracket drag racer and launch the car on first sight of the 3rd amber bulb as the christmas tree is coming down. i want to make ten LED light using time delay feature having fed one by one after specific time day. Bird Sound Generator Circuit Using Arduino Bird Sound Generator Circuit using Arduino This is the schematic diagram of the birds sound generator. Can you tell me whether this is possible, and, if so, how would I go about doing it? Could you please help me to figure out this issue. It says “AVR: Program property is not defined” and also “Real time simulation failed to start” because due to quarantine, we cant try it with the components. The first circuit you showed, with the single transistor, would seem to fit the bill, but I have no idea which transistor and capacitor to use. I have the output from the LM358 feeding a NPN transistor that grounds a 555 one shot, but it never shuts off due to the input from the LM358 being continuous. I will need an adjustable time delay (possibly displayed time) after the switch is released, then the output would go on for an adjustable time (also possibly displayed) before shutting off. The reason for the delays is that the MP3 player takes a few seconds to turn on, then I have to bridge the play button to get it to play the song. 2. Your solution sounds like the alarm circuit negative line would only be connected to negative power when the transistor is turned on. The way I am trying to do it is to charge a capacitor and keep it charged while the signal is coming from the track, if the wheel misses for a second the capacitor would start to discharge but it will see the signal again and recharge so not get to the point when the relay closes till it has seen no signal for about 3 seconds. When the photo cell goes dark and turns the LED on, I would like a timer circuit to turn the LED off after an adjustable period of 4 to 5 hours. Could you explain what a suitable "BJT stage" would look like? you are right mate, just reduce the 1000uF capacitor to something like 1uF, or even less to get the intended small delay effect. I will collect a lot of circuit electronics to teach my son and are useful for everyone. This is small, compact, and portable. It is also an Astable multivibrator circuit on CMOS chip. If i press the button for X time the out get high after x time. Your email address will not be published. I have some bulbs from a company called Imtra that does this, but they do not make light strips and I would like to achieve the same results. I think it can be possible using discrete parts, but while pressing the button some time will be used, so that much time may affect the end result…suppose you take 2 seconds to press the button 5 times, then this 2 seconds will affect the output delay time. 3. Hi, for the mentioned requirement you can modify the delay ON timer by including another BC547 transistor. so there should be another button which can be pressed after the trigger button is pressed 5 times, this idea may help to get the correct delay results. Could you please give me some advice on what would be the best type of circuit to put together for this application? for 30 minutes you can just skip one output of the 4017. make sure to connect pin15 with pin10 of the IC 4017. how would i do a circuit like this that turn off 5 seconds after being turned on with a 12v source? hi can you suggest to me a simple circuit with 15 components for me as an electronics student …………pls i know u can help me…, https://homemade-circuits.com/2012/04/semi-automatic-water-level.html, Good morning sir, I am totally confused with so many timer/delay ckts. The 47K resistor allows pin 2 to be grounded and then pin 3 goes high. Meaning, the relay should be ON initially then OFF after the set delay is elapsed. What I am looking for seems simple, my 9V boat alarm to shut down automatically after 2 minutes, so when I am not at home, the neighbourhood does not go completely haywire. What kind of solenoid are you using, a spring loaded one or the one which requires a push-pull opposite supplies for locking and unlocking. I want to create a small, variable delay. What is its purpose? H Norman, that looks just the opposite of a monostable operation. Changing the resister on the transistor base will allow the delay to be adjusted?Using a 12v supply, can you recommend what resistance and capacitance values I should experiment with to induce a delay between 0.1 and 0.5 seconds? The concept is very simple and is explained in the article. I will/can put a flyback diode across the solenoid coil since it does have some bite on discharge! I tried to understand your requirement, but I am having difficulty in getting and executing the stages together in my mind. so to get a 1 sec delay with that circuit what value of R2 & C2 should be used? meaning, break the existing flasher positive connection and put a diode in the middle. Hi, In the second diagram, using a 1000uF and a 2M2 resistor at the base of the NPN should produce a delay of over 2 minutes….if it's giving 0.5 seconds then there could be something seriously wrong with your circuit…similarly with a 2200uF and 3M3 the delay should be well over 5 minutes. second circuit (Delay off timer with BC547 and BC 557) . If power is removed before timeout, the solenoid would deactivate (expected because there’s no power). This will indicate that the train has passed the point A and moved to a point between point A and B. the timing can be varied by altering the input capacitor and resistor at the BC547 base individually or together. Wouldn’t this cause a relay connected instead of an LED to start switching on and off randomly when the voltage passes through a value which is undetermined for ON/OFF state of the relay? Thanks for your help. If you could include the light gate into the circuit would be a bonus. If I used a constant 48V power supply upstream of a DPDT momentary switch that would keep me from having to use the mixer 48V power. I’m wondering whether it would be theoretically possible to do some of the things mentioned above for a potentiometer (for an analog stick on a video game controller). please make a single module….. test it if you succeed then we can proceed for the final integration. Using two separate base resistors ensures uniform sharing of the current and equal response from the transistors, if you use a single the condition may not show any improvement. If you apply 24V Dc in place of 240V AC it won’t work. which is what I want. From what I have found, I sound be able to short the signal for the “off” channel to pins 2 and 3. The above mods will allow you to implement the actions as specified by you…..reduce the 1000uF value for setting the required time delay between the pump and the injector activation. by some trial and error identify the values of R1, R2, C such that T1, T2 are as per your timing specs…that is T1 could be 150 seconds and T2 could be 5 seconds or vice versa. It is famous for making pulse generator and timer. I want a relay to operate when my cars ignition (+ve 12V) is turned on. I hope I understood your requirement. Now I made very simple alarm system (opened door – ON, Closed door – OFF) and additionally installed "jail" doors. It doesn’t work. When C2 charges fully T1 conducts, which switches ON T2, the MOSFET and the solenoid. What if i need to delay the energizing once i hit the switch to about a second or two. in each row there are 4 leds with 1 330ohm resistor wired in serial. Or have I got something wrong? Yes transistors are used as switches. I had the circuit all worked out with LED, buzzer and the relevant resistors and was going to test whether it would work better in a parallel or series configuration. the base is connected with the delay timer NPN transistor's collector via a 10uF capacitor, the base also has a 10k resistor connected with positive. Will have this tried and will revert with feedback once the markets open here for component procurement. Thanks again for you help! You can read more: this 5-30 minutes timer with PCB layout. yes 10k between positive line and Vcc pin of the IC….capacitor across the Vcc pin of the IC and the negative supply line of the IC, positive of the capacitor will connect with the junction of Vcc pin of the IC and 10K. a capacitor keeps getting charged or discharged. But I wondered if there is a way to use a PNP transistor as an NC contact and when it is turned on after the delay it could reset the alarm? I have built a Darlington bridge with two 2N2222 transistors (that's what I had available) and the relay now latches. Because it is small, energy is clean and safe. Then it dawned on me that the circuit would only function as long as the tip of the sword was in contact with the opponent, which would only be a fraction of a second. In dragracing your reaction time on the launch is everything and it is a game of hundreths-thousanths with the big boys, so I have put the transbrake switch on a relay and put a  1100uf  cap combo across the relay to delay its release. I stumbled across your site and thought I could adapt the “delay on” circuit I just need to incorporate an LDR so it delays about 1hr after dark to move the relay from NO to NC and then during the day the LDR allows the relay to go to NO. This essentially would work to eliminate the “hold” input of the stick and simulate it being a very precisely timed button press. NOTE: the resistance of the mic will become HIGH when it detect the sound. Understanding Noise. Sir do you know any other simulator application? Do you think you will have time to design such a circuit and post it on you site? The data lines of the LCD Display are connected to PORT1 Pins. I connected the LED from 5v to the anode and connected the cathode to ground through a 2k2 resistor (to protect LED). Hi Im mark Im trying to make a circuit that will send an OFF signal after x1 seconds then send ON signal after x2 seconds, I thought bout the 555 timer and a relay but how bout looping Could u help me with this. 13V or 4.5V. Learn about the transistor, LDR, LED and more work together as a voltage divider. Now can it be possible by discrete parts ? Hi Swagatam, I am trying to built IOT with esp8266-01 (wifi module) to operate the 5V relay my circuit. This can be set for triggering for the desired length of time….but I could not understand why the alarm needs to be reset? Made up the circuit on a spare bit of Vero board I had, then tested it’s functionality under all conditions. Next, when the mom opens the door the alarm does not sound, and the mom sees only the flashing LED, realizing that the fridge had been opened before by someone. I understand that the alarm will be audible until such time the reset switch is activated in this circuit. Thanks for the speedy reply. You can probably do the following modification to your existing circuit: The base diode can be a 1N4148, and the capacitor can be a 1uF, My fridge at start up draws much power. Thanks Dave, I think the following modification in the previous diagram should perfectly take care of the issue that you facing. And also,can you put a reset switch to clear the alarm once i attended to it…Thank you very much. I have selected them approximately due to the wide tolerance range for transistors. Thanks! Will try. "The alarm just needs to have it's 5v power cut – either + or -. I have never used simulators because I feel they are far inferior compared to a human mind simulation and tests. I have the 2 transistors on a stripboard with 2 bases on the same strip. for an accurate performance you may have to employ an IC 555 based circuit as shown in the first diagram of this article: https://homemade-circuits.com/2016/11/intruder-position-indicator-security.html. next connect a diode from the collector of the delay timer PNP and join it with the LED positive line. (let’s say, 8V for a 12V Relay)? Hi!I need a circuit with auto stop when the dc motor stops. In the second circuit you suggested you have 2 Transistors drawn as NPNs, the BC547 is NPN but the other BC557 I believe is a PNP. Thank you Sir for the reply. Because of the car electronics I don't believe there is a precise voltage charging this cap every time I activate this circuit and precision is key so I bought a power stabilizer off of Ebay that takes 8-15 volts in and gives a consistent 12volts out. The application is Industrial in nature. I also do not know if a capacitor can charge up in the short time that that the sword tip would close the circuit. Let's learn how the above delay ON timer circuit becomes applicable for solving the following presented issue by one of the keen followers of this blog, Mr. Nishant. use separate diodes for supplying the positive voltage to the LED module, one from the flasher and one from the delay timer, this will do the job. Every think is working fine but if I will restart the system wifi get stuck (may be the drawback from load). For 3 V the emitter of the NPN must be directly linked with the ground without a diode. Hi Jill, you can try the following schematic: I forgot to show a 1K resistor across gate/source of the MOSFET. As long as the capacitor keeps the pin2 high, the output pin3 remains low, and as soon as the pin2 becomes low, the output pin3 is pulled is high permanently. Good day Sir, please I need a circuit that when DC supply is given its relay is activated and deactivated immediately. Hi Swagatam, I really don’t understand your last comment with respect to the cd4060. The relays I am using have four sets of contacts, the other three are used for changing the signals from green to red and back. The lights are powered by a single AA battery. If you are looking for a 12V AC adapter, easy project. best regards torben, Hi, you can try the 2nd circuit from this article…you can get even up to 5 hours delay by suitably adjusting the 2M2 and the 1000uF capacitor values, Can I request a circuit where you push a button then ON and OFF are delay powered only with 3v 2032 cell. I tried this with out the transistor pair and it worked, but was weak, so I added the transistor pair. The LM317 is an adjustable regulator IC that designed to many supplies for 1.5A output. The delay circuit and your one shot circuit work fine. Sorry Sir if I am bothering you too much.. my led array consists of 16 leds, divided in to 4 parallel rows. i need a similar circuit but with 1 hour delay. Is there any way I can send it to you to see if it would work? It seems there's something seriously wrong in the connections or the IC may be faulty, because the circuit is extremely standard and straightforward and should start working immediately.pressing the push button should trigger the relay, and switch it off after the predetermined delay decided by the values of the 47K res and 10uF cap, irrespective of the switch position. I haven’t been able to find any example circuits using LDRs to activate a 4060 IC. Any advice would be appreciated. The circuit would have an led to indicate that the alarm had been triggered. Sorry if this is a resubmission. Assistance please. Swagatam, Thanks I have fixed the dropping voltage problem, just replaced the PIT127 with a BC557, as you suggested. I like the 2.3 circuit but I’m wondering if it could be done with just one transistor since the delay is less than 10 seconds. I have a similar requirement, but I need to reset a 5V touch alarm (by cutting power to it just momentarily) after it trips and starts buzzing a piezo buzzer for about five seconds. You may also like it. The problem I have encountered is that when I connect the circuit to the dc side of the Relay, the voltage of the circuit drops from (12vdc to 1.45vdc) to a level that will not activate the relay. Hi, you can use a reed relay and magnet mechanism for sensing the opening or closing of the door. Hi Dave, In that case, simply reverse the configuration. For the alarm by using the buzzer. A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. So I will give a shot to both and see which suits my needs. The collector of the BC327 is connected to the positive rail of the circuit you gave me. In the overhead tank to ensure it does not overflow and also not emptied fully. Thanks. I seek a simple transistor-based timer circuit for use in a car. you can try connecting a 220uF capacitor in series with the LED with a 1M resistor in parallel with this capacitor, this will probably take care of the mentioned situation. Does the choice of transistors have any effect? Also should I run a diode in front of the relay, not currently because all that is there is the on off switch- where will the current go? Initially, for the first time the alarm will sound while installing the system inside the fridge, but once installed, the 555 circuit will sound only when someone opens the fridge door. This way the delay on-switch will result in the reverse, that is, in a circuit that will switch off in 2 minutes after giving power. Here’s a link to the image of the schematic. I wish to make a "firefly" circuit that will light an LED for 10 seconds, turn it off for two minutes, then turn it on again for 10 seconds and so continue. A 470uF cap in connected to pin 2 or pin 6 with the negative leg and the positive leg connected to VCC. I always try to make Electronics Learning Easy. Actually I already have quite a few similar circuits, these can be suitably combined or modified for any preferred water level control operations.. Hi, could you please suggest me a simple circuit for “Delayed ON IC”? Thanks Dave, and glad you could build it without any issues, hope it works in your car also. On depressing the button momentarily, a positive voltage from the supply line enters the base resistor and switches ON the transistor and subsequently the LED. assuming your motor is rated at 220V, you will need a 500 watt inverter, a 12V 150 AH battery and a 18V 20 amp solar panel which you can directly connect with your battery for charging it, although a having a controller would make things more favorable for the battery…. I explain again: when being powered up, the RESET line switches from low to high (0 to +3.3v). The chip will work on 3-4.5v. The function is as following: 1. This circuit may make laughter.