canusa Posted February 17, 2004 Report Share Posted February 17, 2004 ok i'm just experimenting with a few things and i need to know if anyone happens to know the voltage of the logic circuit for the signal lights on my 91 GTP is? it'd be greatly appreciated. thanks -canusa Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted February 17, 2004 Report Share Posted February 17, 2004 Logic circuits? I know these cars' electrical system quite well and I have no clue what logic circuits you speak of. Quote Link to comment Share on other sites More sharing options...
canusa Posted February 17, 2004 Author Report Share Posted February 17, 2004 ok here's what i wanted to do. i want the front signal lights on the GTP to be bright all the time and go dim or even out when i turn the signal light on. i have all xenon bulbs in the front of my car and when the signal lights are on.. all the lights match in brightness (which is what i want) so basically i need an inverted to flip the signal to the lights. so they are bright when not engaged and flash dimmer when engaged. my friend is an electronics guy and he said "a TTL or CMOS chip with the number 7404 will do the job, depending on the voltage level of the logic, if it's between 0 and 5 then it'll work fine" so that's why i'm asking. in all honesty.. i have no idea what he's talking about. he just told me to ask and find out. so if anyone knows how to do this.. it'd be greatly appreciated. -canusa Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted February 17, 2004 Report Share Posted February 17, 2004 Which bulbs are these, the outboard ones (#24) or the inboard ones, which I think are 3157's? Quote Link to comment Share on other sites More sharing options...
canusa Posted February 17, 2004 Author Report Share Posted February 17, 2004 the 3157's . the ones on the inside of the headlights Quote Link to comment Share on other sites More sharing options...
Gearhead43 Posted February 17, 2004 Report Share Posted February 17, 2004 You mean 3057's not 3157's :shock: :!: Quote Link to comment Share on other sites More sharing options...
canusa Posted February 17, 2004 Author Report Share Posted February 17, 2004 right.. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted February 17, 2004 Report Share Posted February 17, 2004 3057, 3157, they're about the same and interchangeable anyway. Anyway, your electronics friend is greatly mistaken. A 7404 can't source the amount of current the bright filament of a 3057 needs. It would fry the chip ASAP. I don't have a schematic in front of me, but I think you can do this: connect park light wire (+ filament for the park filament of the bulb), remove the Ground from the bright filament, and connect the park + wire there. What would happen is this: When Park/Head lights on, bright filament gets + voltage through the park wire. Bright filament is grounded through turn signal switch when turn signals are off. When you turn the turn signal on, the turn signal wire becomes +. Since the bright filament will be getting + on both wires, it shuts off. It will basically work in opposite of the other turn signal lights. This is how the corner lights on my Cutlass are wired, I'm not positive you can do this in the GP, but I think you can. You may need to upgrade to an electronic flasher in this instance. Quote Link to comment Share on other sites More sharing options...
Gearhead43 Posted February 17, 2004 Report Share Posted February 17, 2004 Anyway, your electronics friend is greatly mistaken. A 7404 can't source the amount of current the bright filament of a 3057 needs. It would fry the chip ASAP. Not even if they use an resistors sized to protect the chip? Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted February 17, 2004 Report Share Posted February 17, 2004 Anyway, your electronics friend is greatly mistaken. A 7404 can't source the amount of current the bright filament of a 3057 needs. It would fry the chip ASAP. Not even if they use an resistors sized to protect the chip? Well, you could, but the resistor would be reducing the amount of current going to the bulb. I don't know how much a 7404 chip can source, but I think it's in the milliAmp range. Using a resistor to limit the bulb to say, 500mA or so, will result in a very dim or virtually unlit bulb. A relay would work better for high current inverting. If a totally solid-state solution is required, you could drive a MOSFET using the 7404. Quote Link to comment Share on other sites More sharing options...
canusa Posted February 18, 2004 Author Report Share Posted February 18, 2004 ok well i'm gonna try playing with some of teh wiring.. and i'll let you guys know how it ends up. thanks very much for your help -canusa Quote Link to comment Share on other sites More sharing options...
quaddriver Posted February 20, 2004 Report Share Posted February 20, 2004 Anyway, your electronics friend is greatly mistaken. A 7404 can't source the amount of current the bright filament of a 3057 needs. It would fry the chip ASAP. Not even if they use an resistors sized to protect the chip? Well, you could, but the resistor would be reducing the amount of current going to the bulb. I don't know how much a 7404 chip can source, but I think it's in the milliAmp range. Using a resistor to limit the bulb to say, 500mA or so, will result in a very dim or virtually unlit bulb. A relay would work better for high current inverting. If a totally solid-state solution is required, you could drive a MOSFET using the 7404. how much does the bright filament draw? an amp? any to220 or t03 case switching trans should handle it, drive that from the 7404 (its simple a stupid inverter anyways no? I doubt you can even find ttl anymore, its gonna be cmos and its current source/sink is gonna be around 100ma max per channel, about 300ma max per chip. but you can wire the trans across the inverter so it biases and unbiases withthe logic flop (I do this all the time with leds used as signals, heck, you can even be old tech and fire a relay across the inverter Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted February 20, 2004 Report Share Posted February 20, 2004 I think bright filaments are 27W so that would be about 2.25A. If a 7404 can only source 300mA, the bulb would fry the chip faster than you can blink an eye. Switching trans would work for 2.25A, but a MOSFET's on resistance is so much smaller, the bulb would get more available power and less power loss as heat compared to a bipolar transistor. Either way, a relay would be considerably simpler to use. Although I think in this case, I think he can achieve what he wants with a simple rewiring. Quote Link to comment Share on other sites More sharing options...
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