how! a infrared 'transmitter'
- Status
infra_red_dude
Wire muncher!
a resistor doesn't haf any polarity. it doesn't matter to which end you connect. BC547 is a transistor. its used as a switch to activate the transmitter only when a button is pressed on the remote.
sashijoseph
In the zone
Well sorry for the bad news but the circuit would never work....
1)The IR LED is reverse biased.....swap the anode and cathode.
2)The 4.7k resistor wouldn't allow any(useful) current through the LED.
Considering a working voltage of 1.5v for the LED and say 0.5v across BC547's CE,we have 5-(1.5+0.5)=3v across the resistor which would provide for 3/4.7 = 0.64ma......a more usable resistor would be 56 or 68 ohms which would provide ~40-50ma.
3)There's no base resistor for the BC547 and the output pin of the TSOP is internally pulled up so 5v would be applied to the base.So add a 4.7k resistor to limit the base current and potential transistor damage.
4)Where's the carrier?TheTSOP includes a demodulator so what you have at it's output pin is the data minus the 38 khz carrier. Simply sending this data through the IR LED won't work because the Tatasky unit needs a
38Khz modulated signal from it's remote.So you'll have to modulate the data with a 38khz carrier.
On second thoughts,the carrier filtered out by the TSOP should still be present albeit at a very low level.The BC547 would amplify this along with the data and hence it may work. You need to test though.
5)The transistor employed would invert the signal hence we need an inverter before it so that the final output remains unaltered.You may use one part of a CD4049 hex inverter- buffer.
Whew that's about it.Look at the attachment for a modified ckt.Actually two....one using cd4049 inverter,the other using a transistor inverter.
1)The IR LED is reverse biased.....swap the anode and cathode.
2)The 4.7k resistor wouldn't allow any(useful) current through the LED.
Considering a working voltage of 1.5v for the LED and say 0.5v across BC547's CE,we have 5-(1.5+0.5)=3v across the resistor which would provide for 3/4.7 = 0.64ma......a more usable resistor would be 56 or 68 ohms which would provide ~40-50ma.
3)There's no base resistor for the BC547 and the output pin of the TSOP is internally pulled up so 5v would be applied to the base.So add a 4.7k resistor to limit the base current and potential transistor damage.
4)Where's the carrier?TheTSOP includes a demodulator so what you have at it's output pin is the data minus the 38 khz carrier. Simply sending this data through the IR LED won't work because the Tatasky unit needs a
38Khz modulated signal from it's remote.So you'll have to modulate the data with a 38khz carrier.
On second thoughts,the carrier filtered out by the TSOP should still be present albeit at a very low level.The BC547 would amplify this along with the data and hence it may work. You need to test though.
5)The transistor employed would invert the signal hence we need an inverter before it so that the final output remains unaltered.You may use one part of a CD4049 hex inverter- buffer.
Whew that's about it.Look at the attachment for a modified ckt.Actually two....one using cd4049 inverter,the other using a transistor inverter.
Last edited:
Zeeshan Quireshi
C# Be Sharp !
well u can get IR transmitter and Reciever Circuits pre made from electronic schops , so you'll just have to connect the output of IR reciever to input of ir transmitter n that should suffice u .
u'll get these curcuits at ur general electronic shop or else buy electronics for you and order the Do It Yourself kits from the dealers listed there .
u'll get these curcuits at ur general electronic shop or else buy electronics for you and order the Do It Yourself kits from the dealers listed there .
infra_red_dude
Wire muncher!
yeah, for this circuit quarter watt resistors are sufficient.
Kenshin
meowww meoww
bout the modulator...i think it shud work...but IRs are unpredictable 
so a modulator with a 555 (astable at 38K)...output of which ANDed(7408 ) with the output of tsop..will do
Once i had a prob with tat 4.7K resistor....ckt din work only...later on removed it and voila....dunnu how...theoretically it shud be there....but practially it din worked for me..hehe...from then on i never use tat resistor...heck i dun use IRs also
so a modulator with a 555 (astable at 38K)...output of which ANDed(7408 ) with the output of tsop..will do
sashijoseph said:
Once i had a prob with tat 4.7K resistor....ckt din work only...later on removed it and voila....dunnu how...theoretically it shud be there....but practially it din worked for me..hehe...from then on i never use tat resistor...heck i dun use IRs also
Last edited:
infra_red_dude
Wire muncher!
ppl.... why don't you use RF??? IR is too problematic, as said before!!
Zeeshan Quireshi
C# Be Sharp !
nah , it will cost atleast 100 bucks , considering hw much time and frustrated you're gonna be while soldering circuits or when something doesn't work(which is the case 99% of the time in electronics) .
jj_alukkas
Right off the assembly line
Easy way... get an IR extender...
If u hv experience in electronics, google for its circuit... I hv come across a lot of them...
If u hv experience in electronics, google for its circuit... I hv come across a lot of them...
- Status