Goatman

just read up the 555 ic can go waaaay below 1Hz. I'll design the circuit and show u guys soon!

well, i've just bought my first car. 75 honda civic. the left indicator is broketed so i've decided to redesign both. i'm planning to use a 50% duty cycle 555 timer circut, the one with the 2 diodes. that will drive a relay. which will drive the lights. the timer needs to be 2 Hz, can that be done?

I'm gonna try this motor today http://www.dse.com.au/cgi-bin/dse.storefront/427aa0ae0272ef082740c0a87f9c0719/Product/View/P9004 it has more rpms and more torque @ highest efficiency.

Ok i've installed this motor http://www1.jaycar.com.au/productView.asp?ID=YM2716&CATID=&keywords=motor&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID= the problem is that this motor is about half as powerfull as th old one. Car goes as slow as it did before the high voltage mod. Where can i get a more powerfull motor. The the drivetrain is pretty low, when driving down the hill it is little faster than on flat land, so i need more RPM than i need power. I could get this 6V motor which does 9k rpm at 6v, so at 12V it would do 18k rpm roughly http://www1.jaycar.com.au/productView.asp?ID=YM2712&CATID=&keywords=motor&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID= Any suggestions?

n000 i fried the motor. It started to smoke, drove at close to full speed for 2 metres or so then smoked heavier, slowed down then stopped alltogether. It was good while itm lasted. I'm buying a new motor today tho. Also rated at 12V I can't find any motors the same size that are rated at a higher voltage :(

The tie wrap used to hold it together but i glued the tire on instead. I should remove it, but it adds ghetto-ness lol. I think the tires wil be fine (hopefully) if they wear out it think i'll just buy a new car :). I've tortured this one enough . ;D

more pics

Here's some pics of the completed car. It's literally too fast for it's own good ;D I used a rellay and a bd139. the pcb is glued with hot glue to the frame of the car. all the lifted pads are from the original 4 mosfets which controlled forward, and reverse. with 1 relay i can only have forward. I don't want reverse, because if i don't press reverse or forward i can't steer (remote controll problem). So i just use reverse for steering when i'm not trying to break the sound barrier ;). to sum it up, this is a complete success. Thank you all for helping me out :)

I'll just go with my best friend (bd139). never failed me. i'll connect the relay between the collector and the supply. no worries! At tafe (turtiary and further education) we had a few practicles on setting the offset null on 741s. 9.5/10 times out of ten they don't work. lecturers blame it on our connections. year right. all the bjt amps we build work lol. one time the +ve supply pin got shorted with the negative input internally inside the op-amp. (-ve and +ve inputs were grounded to set the offset null). with a 15V supply a hole got burned between the +ve supply and the -ve input. i left it on, it was so hot i could melt solder with it easily. took about 2 minuts to finally go open cct. it melted my breadboard, lol. lecturer still blamed it on my connections. ::) when i was a kid my dad bought me an elecrical kit where u have all the components in a piece of cardboard with small springs as tyerminals and all u gotta do is connect up the wires like it says in the manual. It came with a dual op-amp 8 pin IC which i have taken out recenlty. the thing NEVER FAILS ME, everytime it does everything i want it to do. Sad it's only marked with 728 and that's it. i tried googling it. no-go. :(

the tires and motor are just fine. no funny smoke... yet i found this car in the trash (had a blown cap) lol. btw, i hate op-amps... the 741 is a menace to get working. sometimes it does sometimes it doesn't. i've tried various ones from differet manufacturers. damn common mode gain aint helping either lol.

yea, that's the way switch mode powersupplies work AFAIK. Thanks, you've saved me destroying the main IC of that RC car. :)

yea i could do that buffer idea. i could use a bd139, bd140 and a 3055. I think i'll just go with a relay tho. cheap and easy. I doubt silicone could conduct better than copper/steel connections inside the relay. Before the mosfet blew up it lost 3 or so volts across it anyways. Is that because of the inductive nature of the motor? Hell yea, i have an athlon 3000+ (1.8GHz) at 2.6GHz which is about as fast as a 4000+. a 4000+ actually runs at 2.4Ghz but it has double the L2 cache (1024kb).

like one of those darlington pair things minus the extra 0.7V drop? HFE=HFE1*HFE2 :D I was thinking thesame thing. if the HFE was say 400 i don't think i would have a problem. I've decided to get a relay. All i gotta do is hook up an opamp with say a gain of 20 and the output will hit supply rails no problems. I've just learned that when the 9V battery is a bit flat that 2V can drop down to just below 1V. with a gain of 20 i can't loose!. surely the 50 or so ohms outa an opamp will drive a relay. With a relay i get no losses as i would with BJTs or MOSFETs. AFAIK relays are quite tollerant. The relay i'm using to turn the pumps on for my computer's water cooling is rated at 12V, it turns on at 5V :o

ok, I hooked up a potty and adjusted untill it went to 1/2 vout. the output resistance of that IC is approx 800ohms is that enough to drive a 3055 without blowing it up?

ok. turns out that unknown transisor had a terminal going to the reverse controlling mosfet which isn't there anymore (I don't intend to replace it). If i get rid of that transistor, the IC is outputing 2.2V (on, 0V off) when Vbatt is 8V, 2.0V (on, 0V off) when Vbatt is 16V The Ic's VCC runs off a sepparate 9V battery. I'm gonna measure the output resistance of that IC to see if it can run a BJT. if it can, i'll hook up a 3055 and see what happens.

The motor is rated at 12V, I used 2x7.2V batteries. 14.4V won't hurt it. If i short the drain and source pins the motor will go. so no high speed switching found here. I need a mosfet that will turn on with 1 or so volts. I tried a unity gain op-amp cct + BJT. didn't work. I don't have a circuit to show u guys because i didn't design it. AFAIK, there is a 6-7V (off-on) output from an IC which goes to a transistor (totally unknown). That transistor outputs 0.3-1.2 (off-on) to where the gate of the original mosfet used to be.

I attached 2 batteries in series to my RC car, blew the power mosfet after a few days of totally insane speeds. I've tried to use a bjt transistor as the input voltage is about 1 volt. Didn't work. The output impendance of the car's circuit is so damn high it's not funny! I'm looking for an n-chanel enhancement mode power mosfet with a really high input impendance and low turn on voltage. or a nice little non-power mosfet that can turn a rellay on for me. I have tried a motorolla IRF520 nch emode mosfet but that has both a too-low input impendance and a too high imput voltage. any suggestions? I am pretty sure the mosfet i blew up is related to the NEC C4305. I can't read the number off the one i blew up because it no longer looks like a transiostor at all :o