Tech Square Technical and speculative discussion of amps, cables and other topics.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Tech Square ]

---

[ Alert Moderator ]

---

Re: Sweet!

Posted by Jacques (A) on September 6, 2006 at 09:41:19

In Reply to: Re: Sweet! posted by Ronnie Ericsson on August 30, 2006 at 13:14:58:

Does that mean the transistor switches abruptly between 0mA (OFF) and 0.6mA (ON)?

Yes. Have a collector load resistor with a value so that, when the phototransistor is ON, a current <0.6mA flows. For example, if your power supply is 12V, to get such a current, you get a resistor 12V/0.6mA = 20KOhms without any margin. So, use a 33Kohm, 5% and you're done.

was thinking of driving some kind of motorized ball-screw actuator (directly off the transistor if possible)

. Not possible: you won't get more than 0.6mA from the phototransistor, which is way too small to move an actuator.

You should use a timer like the 555, directly triggered by the phototransistor. The micromotor can be fed directly from the 555 (100mA output capable). Furthermore, by adjusting the timer delay, the micromotor would run the requested time, and not stop once he has moved the tonearm away from the light detector.
Google out application note about the 555, it is well known by tinkerers., and cost about $0.1.

Perhaps some kind of minimotor..

As for micromotors, you should cannibalize a dead cheap camera. The lens motor is well fit to your need.

This post is made possible by the generous support of people like you and our sponsors:

Crux Audio

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---