## Turn signals for Motorcycle

 Okay here it is simple but I haven't done any EET since 1983. Can anyone tell me the specs to add into the Led Parameters? All we used in '83 was forward current an min/max voltages. It is also unknown at this time if R6 is needed for Flasher load balancing. https://www.circuitlab.com/circuit/6z4bxy/turn-signals/ by kasman57 April 04, 2013 signality Thanks, one of the links led me to a textbook about the spice calculations. Down loaded it; however. It may not answer all of my questions about the parameters that are listed on the edit led parameters. I will read it and see. by kasman57 April 05, 2013 Okay; signality, Completed I hope, current flowing through each leg of the array is very close to the spec of 120ma @ 3.5 volts. 131ma Total operational R is a bit higher than a 1156 I think a 20 ohm 10watt R6 may be enough. https://www.circuitlab.com/circuit/t7d4q9/led-turn-signal/ by kasman57 April 05, 2013 [ cough ] Don’t get me wrong, but any vehicle (to be used on public roads) is the wrong place to play with. You probably play with your life. R6 with 20Ohm and 10W (+…) in your turn indicator? Which mass? The 12V supply will be up to 14,8V regularly. Regards, Sancho by Sancho_P April 06, 2013 Sancho_P Said [ cough ] Don’t get me wrong, but any vehicle (to be used on public roads) is the wrong place to play with. You probably play with your life. R6 with 20Ohm and 10W (+…) in your turn indicator? Which mass? The 12V supply will be up to 14,8V regularly. No offense taken. No I do not play with my life. That is why I want it correct before installing. Lighting is the key to visual recognition of a Scoot. R6 may be to high in ohms but not watts. An 1156 turn/marker bulb is 1.5 Ohms. The voltage supply in the TSSM only releases 12V +/- .15v to the signaling system. My major concern is the current and forward voltages. They need to be balanced for optimum Luminosity! 3.5V 30mA for each Led. The Cree diode is being used by some makers of your links. In arrays of up to 15 Diodes ( 3 x 5) for brake lights. Extremely Bright! Would you pay a High Price for something You know you Can Make? Regards by kasman57 April 07, 2013 If you add a ground to the -ve end of V1 in: https://www.circuitlab.com/circuit/t7d4q9/led-turn-signal/ sweep the voltage of V1 between about 12V and 14.4V and then plot P(R6) in a DC Sweep you'll see that it is quite a high power part. As I said, depending on the type of flasher unit you are using - i.e. if it is a 2 terminal bimetallic strip unit - R6 has to dissipate the remains of the 21W or so that the original indicator bulb dissipates minus whatever power is dissipated in the total of the LED strings. Obviously, if the power in the LED strings is relatively small compared to the original 21W then the power in R6 will be high. Also be aware that strictly there are rules about the exact colour (spectrum) of vehicle lamps so you may have to do some research on acceptable LED colours to meet the vehicle testing requirements in your locality. If it's for a vintage vehicle then you may be exempt but again that may only apply to original - and not aftermarket modified - equipment. :) by signality April 07, 2013 Updated 4/10/13 https://www.circuitlab.com/circuit/xe4ndj/led-turn-signals/ by kasman57 April 10, 2013 Sorry but now you're being silly. 1) Run the DC Solver Look at the currents throught the individual LEDs. Compare against: ABSOLUTE MAXIMUM RATINGS in: http://scn.cree.com/products/pdf/ledlamps/CP41B-WES&WGS.pdf 2) You need to read more about how you feed and control current to LEDs: https://www.circuitlab.com/circuit/mp673a/two-leds-separate-vs-shared-resistor/ https://www.circuitlab.com/forums/basic-electronics/topic/rt582n4q/need-some-help-on-a-project/ by signality April 10, 2013 Yes I have that download. not completed, and The Cree Leds are a four pin Diode. still working on calcs resistors will change I know that. max voltage is 4.4v and reverse breakdown is 5v. @ 4 volts forward there is about 60 ma forward current. this prog does not allow tested parameters as these are, So this is just a sketch board right now. by kasman57 April 10, 2013 Just didn't want you to go off working on a publicised design that was doomed to fail ... The number of pins on the Cree is not really relevant here: there's only one LED in each package. Is your 12V really regulated? Or is it like most vehicle supplies: 12V battery up to 14.4V at max generator output? If it's a stable 12V then you can use lower series resistors than if you have to cope with 12V to 14.4V etc. If it's can be as low as 12V though you probably can't reliably drive 3 LEDs and a series dropper resistor. `3 * Vf max = 13.2V > 12V` End of. Say you want the LED current to vary by no more that 10mA (33%!). Call this delta_Iled. Let's suppose the 12V supply is 12V to 14.4V. Let's do the sum for 2 LEDs per string and ignore the Vf variation with forward current and temperature. Max Vsupply = 14.4 Min Vf_led_string = 6V Min Vsupply = 14.4 MaxVf_led_string = 8.8V delta_Iled = 10mA (14.4V-6V)/Rseries - (12V-8.8V)/Rseries) = 10mA :. Rseries = ( (14.4V-6V) - (12V-8.8V) )/10mA = 520 Ohms See: https://www.circuitlab.com/circuit/ga8gz3/delta_iled_01/ But then the max current is only about 16mA. Try to increase the LED current and then delta_ILed increases. This is why LEDs are usually driven by constant current sources or sinks which are often themselves based on switch mode supplies: https://www.circuitlab.com/circuit/f646vh/2-transistor-constant-current-sink-01/ https://www.circuitlab.com/circuit/7aavyg/constant-current-sink-led-driver-linear-01/ https://www.circuitlab.com/circuit/63wt5z/constant-current-source-led-driver-linear-01/ https://www.circuitlab.com/circuit/872x9p/constant-current-smps-led-driver-01/ Even so, 10 off LED strings @ 30mA each string is only 300mA so you will need that parallel resistor if the flasher unit depends on seeing bulb load. I've also just remembered another potential gotcha with LEDs. An incandescent bulb has a low cold filament resistance so the flasher unit sees an initial very high current as it is connected to the cold bulbs. as they light up the filament resistance rises so the current through the flasher unit drops. Some flasher units may not actually flash if they only even see a roughly constant hot bulb current as defined by the nominal (i.e. hot) bulb power rating of say, `21W/12V` :) by signality April 10, 2013 https://www.circuitlab.com/circuit/bwwf8m/diagrm-of-circuit/ This is the problem I'm Working on! I am considering an lm317(?) Triac(?) Circuit. by kasman57 April 11, 2013 Sorry: typo. Min Vsupply = 14.4 MaxVf_led_string = 8.8V should be: Min Vsupply = 12 MaxVf_led_string = 8.8V by signality April 11, 2013 "This is the problem I'm Working on!" Forget implementation details. Two things you need to establish before you can go further. i) how does your flasher unit behave with different simple resistive loads; ii) what does your 12V supply really do? Is it really regulated to 12V? Or is it like most vehicle supplies: from around 12V battery then limited at 14.4V max at higher generator outputs? Also you need to define what an"1156" bulb is as an electrical load. 12V 21W? You don't need to go as detailed as "A Tungsten Lamp Model" in: http://www.intusoft.com/nlpdf/nl11.pdf but it does give you an idea of how complex a load a filament bulb really is. by signality April 11, 2013 signality Will this work as diagrammed (with low heat) or, is there a different/better way to obtain a constant voltage with a constant current? kasman57 by kasman57 April 14, 2013 oops 3V will operate/energize the Cree Led by kasman57 April 14, 2013 https://www.circuitlab.com/circuit/yjreqe/controlled-voltage-and-current/ by kasman57 April 14, 2013 You should be starting with something like this: https://www.circuitlab.com/circuit/7aavyg/constant-current-sink-led-driver-linear-01/ or: https://www.circuitlab.com/circuit/63wt5z/constant-current-source-led-driver-linear-01/ or simpler still: https://www.circuitlab.com/circuit/f646vh/2-transistor-constant-current-sink-01/ Start with one of these for a single 2 LED string. Play and get the hang of it. by signality April 14, 2013 "This is a nice simple little circuit:" Okay got it to run in dc sim but not dc sweep. Can it be used for 3 Leds in a string (leg) that energize at 3.0v-3.2v. [Used Two (old 1.554V and 1.457V) AA batteries will energize the cree with legs in parallel wire mode.] Also just add another string for a larger array I presume! by kasman57 April 14, 2013 I've edited the example slightly to clarify. It does run in Time Domain but shows current spikes at startup which are artefacts of CLs solver getting it wrong. "Can it be used for 3 Leds in a string (leg) that energize at 3.0v-3.2v." As long as: `V(supply) - V(Q2_C) > n*Vf_led` where n = number of leds Vf_led = max forward voltage of one led then Q2 (and it's little friends Q4, Q5 & Q6) won't saturate and so it'll work as a constant current sink. Note that V(base) ~= 0.6V (where ~ means aprroximately) and V(Q2_C)-V(base) >~0.25V for Q2 to not be saturated. "Also just add another string for a larger array I presume!" Correct. " ... will energize the cree with legs in parallel wire mode." Sorry, don't understand this. As far as I can see from the datasheet: http://scn.cree.com/products/pdf/ledlamps/CP41B-WES&WGS.pdf the LEDs have two anode and two cathode pins. The anode pins are connected together and the cathode pins are connected together. So there's only one way to connect the LED. by signality April 15, 2013 I've also reduced R7 to 1M and it now runs OK in DC Sweep. I tried it with 1M last night and it didn't run then ... Doesn't inspire confidence. :( by signality April 15, 2013 However ..... You still haven't answered the questions posed in: https://www.circuitlab.com/forums/optoelectronics/topic/t92e42e5/turn-signals-for-motorcycle/#comment_4905 Until you do you have no idea if your circuit will work in practice. by signality April 15, 2013 I have researched and asked for an answer from the Manufacturer, No answer to date.. I also need to take a break for other reasons. Will continue in about 1 week. See you then. by kasman57 April 15, 2013 When you come back, could you not make some measurements yourself? A voltmeter and a few high power resistors? P = V^2/R 21W @ 12V = 6R8 21W 15R @ 9.6W 33R @ 5W 68R @ 5W (actually dissipates about 2.1W) See what the flasher unit does with those loads and sling a LED with a 470R in series across too to see if it actually flashes properly. Measure the battery voltage engine off and at mid to high revs. Plot some graphs? :) by signality April 15, 2013 Okay will do! by kasman57 April 16, 2013