Jednostavan timer

[pepi]

Treba mi jednostavna shema timera koji bi 3-4 minute nakon sto ga ukopcam na struju okinuo relej i drzao ga okinutim.

Na sajtu sam nasao 10-minutni timer sa NE555, ali nema nikakvog objasnjenja:
http://www.elektronika.ba/473/10-minutni-timer/" onclick="window.open(this.href);return false;

Hvala

[mataya]

sa potenciometrom podesis vrjeme, umjesto ledice i otpornika dodas relej i to je to

[pepi]

Skuzio sam za potenciometar, ali tu vidim dvije LED-ice. Umjesto koje bih trebao "ugraditi" relej?

[stojke369]

Simulirao sam ovaj tajmer i kad ka upalis nista se ne desava dok ne stisnes taster i on upali zelenu led diodu i tako drzi (zavisi na koliko je podesen potenciometar) i posle podesenog vremena ugasi zelenu i ponovo upali crvenu diodu.Za ponovno pokretanje tajmera pritisnes tastre i on upali zelenu .....

[pepi]

Hvala ti. Znaci mogu maknut zelenu diodu i umjesto crvene stavit tranzistor koji bi palio relej?

edit:
Je li postoji mogucnost da sklop napravim bez tipkala(tastera), tj. kada ga ukljucim u struju da odbrojava?

[Feko]

Ako hoces sa PICom...procitaj prvi i zadnji post samo se malo promijeni program i to je ono što ti treba
http://www.elektronika.ba/forum/viewtop ... 5&start=15" onclick="window.open(this.href);return false;

[stojke369]

Power-On Time Delay Relay

Here's a power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor. The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair. Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used. Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values. Longer delays can be obtained with a larger capacitor, the timing resistor probably shouldn't be increased past 47K. The circuit should work with most any 12 volt DC relay that has a coil resistance of 75 ohms or more. The 10K resistor connected across the supply provides a discharge path for the capacitor when power is turned off and is not needed if the power supply already has a bleeder resistor.

[stojke369]

Power-Off Time Delay Relay


The two circuits below illustrate opening a relay contact a short time after the ignition or ligh switch is turned off. The capacitor is charged and the relay is closed when the voltage at the diode anode rises to +12 volts. The circuit on the left is a common collector or emitter follower and has the advantage of one less part since a resistor is not needed in series with the transistor base. However the voltage across the relay coil will be two diode drops less than the supply voltage, or about 11 volts for a 12.5 volt input. The common emitter configuration on the right offers the advantage of the full supply voltage across the load for most of the delay time, which makes the relay pull-in and drop-out voltages less of a concern but requires an extra resistor in series with transistor base. The common emitter (circuit on the right) is the better circuit since the series base resistor can be selected to obtain the desired delay time whereas the capacitor must be selected for the common collector (or an additional resistor used in parallel with the capacitor). The time delay for the common emitter will be approximately 3 time constants or 3*R*C. The capacitor/resistor values can be worked out from the relay coil current and transistor gain. For example a 120 ohm relay coil will draw 100 mA at 12 volts and assumming a transistor gain of 30, the base current will be 100/30 = 3 mA. The voltage across the resistor will be the supply voltage minus two diode drops or 12-1.4 = 10.6. The resistor value will be the voltage/current = 10.6/0.003 = 3533 or about 3.6K. The capacitor value for a 15 second delay will be 15/3R = 1327 uF. We can use a standard 1000 uF capacitor and increase the resistor proportionally to get 15 seconds.

[pepi]

Hvala Feko, ali radje bi radio sa NE555 jer nemam ni PIC ni programator.
@Stojke, koji simulator koristis?

[Feko]

Onda ti je to bolje riješiti sa kondenzatorom i tranzistorima kako ti Stojke predlaže...no možda se može i sa 555 nekako zaobići taster...tko je više radio sa 555 neka ti riješi shemu
no dali možeš dobiti 3-4 minute koliko je tebi potrebno...veliki veliki kondenzator

gle...evo ti sa 555
http://www.elecfree.com/electronic/powe ... ts-by-555/" onclick="window.open(this.href);return false;

...goooooogle

[stojke369]

Simuliram u Livewire

[buco22]

Tu imaš sve što ti treba

http://www.uoguelph.ca/~antoon/gadgets/555/555.html" onclick="window.open(this.href);return false;