tag:blogger.com,1999:blog-6615160292280278140.post1099515753364682623..comments2024-03-28T08:07:01.529-04:00Comments on Hands On - Make: Electronics: Chapter 2 - Exercise 11 Step 1James Floyd Kelly (Jim)http://www.blogger.com/profile/13876934942928389738noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-6615160292280278140.post-17507305478339382032010-11-26T15:12:38.160-05:002010-11-26T15:12:38.160-05:00I wired up this circuit this morning, and it worke...I wired up this circuit this morning, and it worked as described -- blinked quickly with the 2.2uF capacitor and slowly with the 22uF capacitor. I even clamped my multimeter leads to the capacitor and was able to observe the build-up and discharge.<br /><br />Then I tore the circuit apart and had my son rebuild it. Worked as before EXCEPT we can't get the capacitor to discharge when the multimeter is connected -- builds up to about 4.2V and then just sits there. As soon as I disconnect the multimeter, the LED flashes and all returns to normal.<br /><br />Best I can figure is that the multimeter is eating up a little voltage and not allowing the capacitor to build up as much as it should to exceed the PUT's gate threshold.<br /><br />Tried switching the power to a higher voltage, but got a similar result (I'd assume because the higher voltage is causing the PUT's gate threshold to proportionately increase).<br /><br />I tore apart the circuit and rebuilt it, and also validated the values of the resistors.<br /><br />Once again, we got the point of the exercise and will thus probably just move on to the next one.Thrallhttps://www.blogger.com/profile/14857436453066969832noreply@blogger.comtag:blogger.com,1999:blog-6615160292280278140.post-84974648869049372532010-04-10T23:14:42.466-04:002010-04-10T23:14:42.466-04:00I bought the big bundle of resistors too. Then I b...I bought the big bundle of resistors too. Then I bought a fishing tackle box to sort them into. I sorted them using the color code and then testing them with my DMM just to see if I was any good at reading the color code. I wasn't at first.<br /><br />After I measured each group of resistors, I wrote the nominal and measured resistance on the tape strips. Then I sorted them into the tackle box according to the third color band. It was kind of a boring task, but I just did a couple of groups at a time over several days and it was not too onerous.ctdahlehttps://www.blogger.com/profile/03301494095196099233noreply@blogger.com