Search found 32 matches

by Craig Kendrick Sellen
Sun Jun 10, 2007 8:58 am
Forum: General Discussion
Topic: How do I Fine tune a 78L05 ?
Replies: 50
Views: 11996

78L05 Regulator 5 volt on the nose

Dear DIMBULB; I calulate on my calulator it's only 5mV differance. How crrital is it? You can put a Schottky barrier diode between ground and ground of 78L05 but thats only 100mV differance. Or make a custom regulator by using a PN2222A transistor and a pot. say 10K and at least a 1K in series with ...
by Craig Kendrick Sellen
Sun Jun 10, 2007 8:43 am
Forum: General Discussion
Topic: NEED FORMULA TO FINS FREQ. OF OSCILLATOR
Replies: 24
Views: 6536

triangle & square wave osc.

Dear BOB, or MrAI or anyone eltz. :sad:
I think I made a misscalation The oscillator should run at 500 to 540Hz, using back to back 22uF's. Can you recalate? PLEASE? :eek: CRAIG
by Craig Kendrick Sellen
Wed Jun 06, 2007 1:18 pm
Forum: General Discussion
Topic: NEED FORMULA TO FINS FREQ. OF OSCILLATOR
Replies: 24
Views: 6536

I worked out the resistor network. (see attachment)
Image
by Craig Kendrick Sellen
Mon Jun 04, 2007 7:06 pm
Forum: General Discussion
Topic: NEED FORMULA TO FINS FREQ. OF OSCILLATOR
Replies: 24
Views: 6536

triangle-squarewave generator

To, Mr. AI, Bob Scott; Thanks for answering my request for help. Heres the frequency I need. First C1, C2 can be one componnet. The pot. only needs to vary a little, so a small range say 500 ohms. Inore R3, R4. The frequency if from 1Hz to 18.5Hz If you can plug in the values, it will be a big help....
by Craig Kendrick Sellen
Sun Jun 03, 2007 7:52 pm
Forum: General Discussion
Topic: NEED FORMULA TO FINS FREQ. OF OSCILLATOR
Replies: 24
Views: 6536

NEED FORMULA TO FINS FREQ. OF OSCILLATOR

Inclosed is a circuit for a op-amp oscillator that puts out triangle and squire waves. My question is what is the FORMULA for this circuit? Ignore R3, & R4, both pins are grounded. I just need the correct formula for this. http://upload8.postimage.org/660947/formulaforoscillator.jpg :grin: :smile: :...
by Craig Kendrick Sellen
Tue Apr 03, 2007 8:48 am
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

it's me again with new approuch

This one is a bit more involed, uses LM393 dual comparator, and two transistors. When S1 and S2 are both open nothing happens, relays are off. First when S2 is closed the relays pull in, OK. Now when S2 is open the relays are off. Now when the relays are in S1 is closed it's set for a turn off for a...
by Craig Kendrick Sellen
Tue Apr 03, 2007 6:30 am
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

my circuit using LM311N instead of op-amp

HELLO MrAI; Im posting another circuit using LM311N. The values will have to be droped in. Rember it uses a PNP. The only thing I didn't think of is maybe it needs a pullup resistor to V+ to pin 7. (see schematic below) What I need is when S2 is closed the relays pull in regardless of LM311N. But wh...
by Craig Kendrick Sellen
Mon Apr 02, 2007 4:39 pm
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

my circuit

Dear MrAI;;; see revised circuit below. Is this OK with you. Which resistors from the output of op-amp does the 250 ohms and 2.5K? Which one is grounded, and which one goes to op-amp? I just had a thort, how bout a ZENER diode in the emitter of the transistor, with the anode to the emitter. With a r...
by Craig Kendrick Sellen
Mon Apr 02, 2007 2:25 pm
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

my circuit

Dear, MrAI I will slid the diode down to the junction of S2 (drop) and base of the PNP transistor, in other words in place of the 1K. And I will omit the 1K resistor. The 470 ohm resistor is a limiting resistor, so when the drop switch is closed the relays will pull in and stay on until pin 6 of the...
by Craig Kendrick Sellen
Fri Mar 30, 2007 9:17 pm
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

question about circuit

I revised the circuit again and reduced parts count. I replaced the LM311N with a conventional LM741 op-amp. The pot. is to adjust the thrushold or trip level, while the + input goes to the slowly rising voltage in the positive direction. See circuit diagram. Inregards to the relays, I plan to use D...
by Craig Kendrick Sellen
Fri Mar 30, 2007 12:53 pm
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

question about circuit

THANKS TO ALL OF YOU FOR YOUR HELP. I POSTED A NEW MODIFIED CIRCUIT, IS THIS BETTER? JUST CHECK THIS OUT PLEASE. THE ONLY QUESTION I HAVE IS DO I HAVE THE + AND - ON THE COMPARATOR LM311N RIGHT? OR DO THAY NEED TO BE REVERSED? I OMITED THE 555. AND REPLACED IT WITH A PNP TRANSISTOR. QUESTION DOE'S A...
by Craig Kendrick Sellen
Wed Mar 14, 2007 9:40 pm
Forum: General Discussion
Topic: Q&A colum in N&V is no more or.?????
Replies: 17
Views: 4541

IS Q & A colum gone

In regards to the Q & A colium, if Nuts and Volts drops the Q & A I think I will let my subscription to N & V expire. Im so sick of digital and PIC projects! I am a analog man and can't sell any articles to electronics magazines because thay don't anything analog anymore, thay want digital PIC proje...
by Craig Kendrick Sellen
Fri Mar 02, 2007 10:40 pm
Forum: General Discussion
Topic: QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW
Replies: 16
Views: 4659

QUESTION ABOUT CIRCUIT, WANT TO REPLACE OLD CIRCUIT WITH NEW

Can anyone make the new circuit function same as the old circuit? (SEE ATTACHMENT) Dear Sir's and Madams; and the Q and A colume of NUTS and VOLTS magazine. I have a question about a circuit that should have gone to TJ BYERS but need someone eltz to answer my question? It's part of a bigger circuit ...
by Craig Kendrick Sellen
Fri Mar 02, 2007 1:27 pm
Forum: General Discussion
Topic: TJ Byers passing
Replies: 13
Views: 4327

TJ BYERS passing

I am shocked about TJ's passing. I sent him several e mails or letters and he whould allways publish them and answer my requests. He's gone with Herb Friedman of Electronics Iustillrated. Is Louis E. Garner around yet or is he gone too.
craig kendrick sellen
by Craig Kendrick Sellen
Tue Feb 27, 2007 10:05 pm
Forum: General Discussion
Topic: Does anyone know if I can get ELECTRONICS IUSTILLATED
Replies: 5
Views: 1726

Does anyone know if I can get ELECTRONICS IUSTILLATED

IS THERE SUCH A PLACE WERE YOU CAN GET BACK ISSUES OF ELECTRONIC MAGAZINES SUCH AS ELECTRONICS IUSTILLATED, RADIO & TV EXPERIMENTER, ELELAMENTRY ELECTRONICS, AND POPULAR ELECTRONICS BACK IN THE 50'S & 60'S ON MICROFILM OR MAYBE CD? :eek: http://www.msnusers.com/103pennywhistler http://upload6.postim...