Search found 1549 matches

by dyarker
Thu Nov 01, 2018 1:32 pm
Forum: Robotics
Topic: How to extract the pulsed output from Servo motor and send to wireless converters
Replies: 1
Views: 1181

Re: How to extract the pulsed output from Servo motor and send to wireless converters

Are you talking about servos that set the position of the output shaft based on pulse width of the input pulses? What does the wireless analog to digital converter (ADC) have to do with pulse width control? ADCs convert a level to a digital number. The pulses to a servo are at ON level or OFF level;...
by dyarker
Tue Oct 30, 2018 3:05 pm
Forum: General Discussion
Topic: Lithium Ion charger hack..
Replies: 7
Views: 1111

Re: Lithium Ion charger hack..

Two components and three connections complicated????? The NTC is in physical contact with cells. It's resistance changes with temperature OF THE CELLS. The junction of NTC and a fixed resistor is wired to (pin 1?) of the IC. The IC circuitry measures the voltage to control the charge current. The ot...
by dyarker
Wed Oct 24, 2018 7:30 am
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

sure! the bulbs will be too much current for 2N3906s, so use LEDs and 1K resistors.
by dyarker
Wed Oct 24, 2018 4:17 am
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

Schmidt2LEDs2.png
Last night 20 logins, nothing; today 2 like you said.
by dyarker
Tue Oct 23, 2018 6:22 pm
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

try to attach schematic, get logged out
by dyarker
Tue Oct 23, 2018 3:22 pm
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

Without R3 the circuit is not a schmitt trigger anymore. The Q1 base resistance to negative supply is like 1 or 2 Ohms (bad!). With R3 the base resistance is like 50K to 100K (no burnt pots). R3 being "shared" with Q2 causes the "snappy" switch between which transistor is on. It is better to put ori...
by dyarker
Mon Oct 22, 2018 7:44 am
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

Looking at it again -

What else have you done?

R3 times the gain of Q1 should have prevented pot burn-out.

What colors are the bands on R3?
by dyarker
Mon Oct 22, 2018 7:09 am
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

Putting a resistor in parallel with the pot will not save the pot. Is just passes more current around the pot. The excessive current through the pot at low setting stays the same. I left the 10K in to give the original 2 seconds when pot at zero. I do not know what size (in Watts) your pot is But if...
by dyarker
Mon Oct 22, 2018 6:55 am
Forum: General Discussion
Topic: Amplifier LM358—classical circuits
Replies: 5
Views: 1113

Re: Amplifier LM358—classical circuits

? The point is that that operational amplifiers may be used for a large number dissimilar jobs. In this case the LM-358 specifically, which has two op-amps in one package. They may be used together, or separately. To get more detailed explanation search on name of curcuit type like op amp vco, or op...
by dyarker
Wed Oct 17, 2018 3:41 am
Forum: General Discussion
Topic: A Simple but Accurate Constant Current Source
Replies: 19
Views: 4312

Re: A Simple but Accurate Constant Current Source

The battery symbol in the schematic is upside down.

The short line represents the cathode (negative), and the long line the anode (positive).

Cheers,
by dyarker
Mon Oct 15, 2018 11:52 am
Forum: General Discussion
Topic: Forum Update! Upgrade & Attachment Uploads
Replies: 5
Views: 716

Re: Forum Update! Upgrade & Attachment Uploads

If you have the "Insert Image" button above the text entry box, then you are in Full Edit mode. That button is for images on another server somewhere. Don't touch it! Go below the text entry box. See the "Submit" (and 2 others) buttons about in the (side-to-side) center? A little lower on the left a...
by dyarker
Mon Oct 15, 2018 4:58 am
Forum: General Discussion
Topic: Need help with a circuit again
Replies: 29
Views: 2965

Re: Need help with a circuit again

Schmidt2LESDs.png Testing "Attachments". Might still be useful. The only change from previous circuit is pot in base's path of Q1. Important - use "Inline" button to put attachment tags in the reply. Cheers, P.S. Thanks T&L/admin, should make some real happy. Works and was easy to figure out how to...
by dyarker
Thu Oct 11, 2018 7:14 am
Forum: General Discussion
Topic: How to tell it is good?
Replies: 8
Views: 948

Re: How to tell it is good?

... shall I need a heat sink?
Maybe.

Need input (supply) voltage, regulated output voltage, max current to be drawn, which part number regulator and package. For example, an LM350 in TO-3 may handle more power than TO-220.
by dyarker
Wed Oct 10, 2018 7:49 am
Forum: General Discussion
Topic: How to tell it is good?
Replies: 8
Views: 948

Re: How to tell it is good?

What is the "35"? The max and 4.2V the min? With two 9V in series the max available with "near the end" batteries is 12V. 18V fresh. And LM350 needs about 2V difference between supply in and regulated out; so max out is 10V to 16V depending on freshness. With 9V batteries the max "sustainable" (a do...
by dyarker
Tue Oct 09, 2018 4:51 am
Forum: General Discussion
Topic: How to tell it is good?
Replies: 8
Views: 948

Re: How to tell it is good?

How much is load current? Output voltage range needed? Is 9V battery the primary supply? What is resistance of poteniometer?