Search results

Search Forums New Posts
  1. CDRIVE

    My New Toy

    Do yourself a big favor. Don't buy any bike until you've mounted a Trek Pure. I've had this beauty for only 12 days and have logged 80 miles on it! The geometry and ergonomics of the Pure are unique. Riding a bike should be fun and she is one fun party girl! This is the first bike I've...
  2. CDRIVE

    My New Toy

    Yes guys, I'm fortunate to have great biking weather, flat terrain and sidewalks just about everywhere. My bride and I ride mostly on sidewalks but intersections can be deadly. In fact I've come to the conclusion that it's safer to cross a divided roadway anywhere but the intersections! Whether...
  3. CDRIVE

    Model engineer needs help

    I'm afraid it will disappoint everyone. It's not a new lab instrument. Heck, it's not even electronic. It isn't machine/wood shop related either. https://www.electronicspoint.com/my-new-toy-t255135.html Chris
  4. CDRIVE

    My New Toy

    While in a Circuits forum thread I mentioned that I was distracted by a new toy I just bought. Stew1954 wanted to know what it is. So...... When at my last checkup with my GP he informed me that I gained 25 pounds since I retired a year ago. I was overweight when I was still working, so I...
  5. CDRIVE

    LED insertion

    When you post a reply just click on the paper clip on the tool bar. It will bring up the attachment manager. Chris
  6. CDRIVE

    LED insertion

    Post the schematic less the LED and indicate where the LED nodes are connected.. Chris
  7. CDRIVE

    Control circuit

    Curious; what will you be powering that requires 24VDC? Chris
  8. CDRIVE

    LED insertion

    What are you trying to do? Chris
  9. CDRIVE

    Control circuit

    Draining them that low you will likely damage the batteries. Chris
  10. CDRIVE

    Model engineer needs help

    Stew, unless you have this project also posted on another forum, thus getting information elsewhere, you're a quick study! I guess I shouldn't be surprised, as model engineers are not dummies. Yes, the diode should work. ;) I'm very disappointed in myself for not considering the two spare...
  11. CDRIVE

    Model engineer needs help

    Yes, I'm on my 4th cup of morning coffee but I'm still confused. Today is Saturday so later this afternoon I'll be dumb as a box of rocks. :p I think the easiest way for me to comprehend the logic you want is for you to answer this. When the tank is low do you want the PNP (T1) to be...
  12. CDRIVE

    Model engineer needs help

    I thought you posted your photo transistor (PT) circuit early in this thread but I can't find it. Considering the logic at the input of the OpAmp I'm assuming the PT is wired as Common Emitter. If I understand you correctly you can shunt the collector of of the PT with an NPN. When the NPN is on...
  13. CDRIVE

    Model engineer needs help

    I used one in my last schematic too but I was able to make it 47K because of the two diodes. The larger R2 is the less wasted battery current. Steve has been arguing that there's no path to ground when the 358 is high. Therefore it will not pull base current to turn on the PNP. I understand...
  14. CDRIVE

    Model engineer needs help

    Steve, I've used an LM555 as an analogy three times already. At the risk of sounding like a broken record a 555 is not sinking when it's high and it presents the same issue when it drives a PNP base. It's output is < .7V lower than the emitter that's connected to the Vcc. Honestly, I thought...
  15. CDRIVE

    Model engineer needs help

    The 358 pin-out numbers will be different from your last schematic but other than that the diode scheme should look like this. See note below. Fixed that! Since you had a melt down I'd test your components before wiring this. Chris Edit 1: Renumbered LM358 to conform to Stew's OpAmp...
  16. CDRIVE

    Model engineer needs help

    Molten insulation!!?? You're obviously doing something wrong. Not knowing what you did wrong I can only guess but if this extreme current passed through any part of the transistor or the 358 they're probably toast. I'll post a schematic soon. Chris
  17. CDRIVE

    Model engineer needs help

    Stew will be lucky if the output swings much above 4V. The PNP will always be on, Two diodes should eliminate the issue. I really don't see anything odd about what I'm saying. Diodes are used for this purpose all the time. Chris
  18. CDRIVE

    Model engineer needs help

    Steve I'm not sure we're on the same wave length. You're saying that an LM358 with Vcc = 5V is capable of swinging all the way up to Vcc? I don't think so. I don't even see so called "Rail to Rail" OpAmps doing it. His PNP will have the same issues that PNPs have when connected to a 555 output...
  19. CDRIVE

    Model engineer needs help

    Stew, we'll just spin our wheels if you keep doing this. The circuit I posted should work. Rleo6965's circuit should work. I didn't examine yours closely so I won't comment on if it should work. If they're not working we have to ascertain why. Chris
  20. CDRIVE

    Model engineer needs help

    That will work but from a minimum battery drain perspective diodes are a better choice. ;) Stew, what are the max - min voltage specs of your servo, model number? FYI, the TLC555 (CMOS) specs Vdd = 2V min to 15V max. Chris
Top