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Author Topic: Follow me home  (Read 5422 times)

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York

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Follow me home
« on: May 15, 2011, 00:27:10 AM »
Hi, I have this 'follow me home' idea :D

This is quick schema how it would look like, I dont know how to calculate exact part values so please if someone can help.

This is the theory; When key position is zero or key is out the first (from the left to right) relay give contact to the board, and then if driver give a blink with headlights, capacitor does his job. Idea is that capacitor can handle the second relay in position ON for about 10 sec, while the fog light or any light we want goes ON for that time (10 sec).

When key is on position 1 or 2 first relay shuts down the board, so that while we drive lights goes normal as it should.




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kam

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Re: Follow me home
« Reply #1 on: May 15, 2011, 18:08:05 PM »
for some reason i cannot view the image in full size. please re-upload.

_pike

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Re: Follow me home
« Reply #2 on: May 15, 2011, 21:31:47 PM »
me too......!!!! An adverstisment pops up.

York

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Re: Follow me home
« Reply #3 on: May 15, 2011, 22:46:59 PM »
OK here is new img file uploaded :)


If you need I can upload file from eagle on Linux...



Today I had try two Mosfet types but they dont give me enough power to start relay (12V), either Mosfet is connected to 12V power supply, and gate pin goes to 6V. They can make small bulb goes on, but relay stays OFF...



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_pike

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Re: Follow me home
« Reply #4 on: May 16, 2011, 10:22:30 AM »
You can use this circuit.........   http://pcbheaven.com/circuitpages/Car_Dome_Light_Off_Delay/ 
or you can built a circuit with a 555 timer circuit as a Monostable Multivibrator which kam has a very detailed description in http://pcbheaven.com/wikipages/555_Theory/

kam

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Re: Follow me home
« Reply #5 on: May 18, 2011, 08:26:54 AM »
The relay needs a specific voltage to operate, so the second relay (K2) will either flicker or not arm at all if the R1/R2/R3 network does not prvide sufficient voltage (12 volts). And as a matter of fact, they wont provide the voltage needed because it will be little less than 12 volts.

So what you need to use is a monostable circuit, maybe with a 555 timer. Check it out here:
555 Circuits- section Basic monostable circuit
And the theory:
555 Theory There is something interesting at the bottom.

York

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Re: Follow me home
« Reply #6 on: June 04, 2011, 23:25:03 PM »
Tonight I have connect this schema from the link above and results are not good

:)


First the general use diode has gone in smoke :p , then I try it without that diode and I saw smoke again, this time from switching diode lol

kam

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Re: Follow me home
« Reply #7 on: June 05, 2011, 08:47:34 AM »
which schematic and which diode>

York

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Re: Follow me home
« Reply #8 on: June 16, 2011, 22:08:23 PM »
Sorry for my late response,

first to say, those parts I have used was not exact parts you guys used :)   that is the reason for burning effect.

Now I have bought some components :

1/4W 2k2
1/4W 33k
1N4007 - I couldn't find 1N4002 so please let me know is this diode good replacement
1N4148
BD239 - I couldn't find BD243 so again, please let me know is that good replacement
BC547
and finally I don't have BD140 and I don't know which one to use instead

_pike

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Re: Follow me home
« Reply #9 on: June 17, 2011, 01:13:51 AM »
hi!
     
1N4007          ok
For the BD243 use -->BD244
For the BD140 use -->BD136 or -->BD138

BD239:
VEBO        Emitter-Base Voltage                      5 V
IC           Collector Current (DC)                     2 A
ICP         *Collector Current (Pulse)                4 A
IB            Base Current                                  0.6 A
PC           Collector Dissipation (TC=25°C)     30 W
TJ             Junction Temperature                    150 °C
TSTG        Storage Temperature                   - 65 ~ 150 °C

BD243:
VEBO      Emitter-Base Voltage                   5 V
IC           Collector Current (DC)                  6 A
ICP       *Collector Current (Pulse)              10 A
IB           Base Current                                 2 A
PC          Collector Dissipation (TC=25°C)   65 W
TJ            Junction Temperature                   150 °C
TSTG       Storage Temperature                  - 65 ~ 150 °C

As you see there is current resist issue.I don't know if the amperaze is ok.How much watts is the dome lamp?Kam what do you say are 2amps enough?(with a heatsink?)
« Last Edit: June 17, 2011, 01:18:34 AM by _pike »

kam

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Re: Follow me home
« Reply #10 on: June 22, 2011, 07:45:42 AM »
one remark. If you are talking about this schematic: http://pcbheaven.com/circuitpages/Car_Dome_Light_Off_Delay/
and the diode smoked, this means that either the diode is connected incorrectly, or the whole circuit is connected incorrectly. If i was to bet on one of these two, i would bet on the second. I'm afraid that the circuit was incorrectly connected and that is why the diode smoked.