10k potentiemeter connections - Page 1
Forum section: electronics / beginners

author: RobH
author_rank: Regular Contributor
timestamp: December 01, 2020, 05:31:11 pm
content: On other simple circuits which have included a 555 ic, I have connected the middle pin of the 10k pot to pin 2 on the 555ic.while the 2 outer pins are connected to +V and -VOn this schematic it shows a 1k resistor connected to pin 1 on the 3 pin 10k pot, then shows pins 2 and 3 connected, and then pin 3 to +5V.In practice, what should be the actual connections, as I'm a bit confused.Thanks

author: TimFox
author_rank: Super Contributor
timestamp: December 01, 2020, 05:59:18 pm
content: The circuit you posted uses the potentiometer connected as a variable resistor in series with the fixed resistor in the timing circuit.Your previous connections used the part as an actual potentiometer to apply a variable voltage to pin 2.

author: Benta
author_rank: Super Contributor
timestamp: December 01, 2020, 05:59:50 pm
content: The term "potentiometer" implies your first description of your circuit.The schematic shows a potentiometer connected as a variable resistor, which is not the same function (but the same device).

author: Benta
author_rank: Super Contributor
timestamp: December 01, 2020, 06:00:40 pm
content: Jeez, TimFox, we should start a club

author: TimFox
author_rank: Super Contributor
timestamp: December 01, 2020, 06:40:13 pm
content: Great minds think alike, yet fools seldom differ...

author: RobH
author_rank: Regular Contributor
timestamp: December 01, 2020, 06:41:01 pm
content: Ok thanks but is the resistor connected to the middle pin of the pot, pin2, and then an outer pin to +V. Is that it, nothing else.Thanks

author: TimFox
author_rank: Super Contributor
timestamp: December 01, 2020, 06:57:19 pm
content: When connecting a three-terminal potentiometer to make a two-terminal rheostat (q.v.), it is normal to connect the wiper to one end of the resistance element, to avoid momentary open-circuit high-resistance events if the contact be noisy.

author: RobH
author_rank: Regular Contributor
timestamp: December 01, 2020, 07:02:22 pm
content: Thank you and that is how I have it connected. I just wanted to be sure when I asked my question.One other thing, is there anyway I can check that the circuit actually works, as this is the transmitter for a long range IR detector. I have built the receiver and that seems to work ok.I don't have any test equipment, apart from a multimeter.Thanks

author: alsetalokin4017
author_rank: Super Contributor
timestamp: December 02, 2020, 05:28:53 pm
content: Quote from: RobH on December 01, 2020, 07:02:22 pm??The circuit in the OP is a receiver, isn't it?Anyhow, many cellphone cameras can see the light from many IR LEDs, so you could try looking at your transmitter's IR LED with your camera. Try both the front cam and the selfie cam.

author: RobH
author_rank: Regular Contributor
timestamp: December 02, 2020, 06:44:42 pm
content: Yes the circuit is a receiver and has a TSOP 1838 IR Receiver .My phone, Huawei nova 5T, camera didn't pick anything up from it and the selfie camera , well, it was just me, lolIs there anywhere I could connect a LED. I've had a look round the circuit with a multimeter and the voltages are mostly 5v nominally.The relay I am using is a SPST with just 5 pins.Thanks

author: Brumby
author_rank: Unknown
timestamp: December 02, 2020, 11:11:01 pm
content: The phone camera trick won't work on IR receivers - just IR transmitters. (Works well - I've used this many times.)If you want to check if the receiver is picking up a signal, I'd probe the output pin of the receiver on a scope (assuming you have access to one).

author: RobH
author_rank: Regular Contributor
timestamp: December 03, 2020, 09:26:27 am
content: I tried my phone camera on the transmitter and , unless I was mistaken in some way, I saw what appeared on the led a small / tiny light blue dot near or at the top of the IR led. Or is that just the reflection of the camera??No I don't have access to a scope at all, and don't know anyone who has one.I fear I might have bitten off more than I can chew with this project / circuit.Thanks