Hi,
Please could someone cast an experienced eye over the attached circuits? A raw beginner's attempt at combining (very) simple building blocks.
Here is the plan. To transmit a brief signal about 50 ft (15 m) when the temperature at the far end of my garden goes above 25 C, and to transmit another brief signal when it falls below 25 C. The 27 MHz crystal was chosen in order to stay away from the FM band, so not to disturb the neighbours' FM listening. The "brief" signal is to ensure that the toys in the neighbours' houses didn't wake up and get rowdy. Transmitter in the garden, receiver in my house.
For the transmitter, I tried to follow 27 MHz Transmitter | CircuitDiagram.Org. That circuit doesn't show where to attach V+ and GND, so I guessed.
For the toggle on the receiver, I tried to follow "Single MOSFET Toggle" from Circuits Page 9.
If it helps, here are the resistances for the B57891 10K 5% thermistor.
C ohms
24 10446
25 10000
26 9578
Using 2% resistors. I reckon the 560-ohm resistor will give about a 1-degree-Celsius window. And the temperature will go from 24 C to 26 C (or v.v.) in about a second. I'm aware of one fatal flaw -- where temperature goes from 23 to 25.1 and back to 23 -- but I'm willing to live with it, as a rare event.
The dual opamp's output will be "on" for probably no more than 30 seconds a day.
Anyhow, will these circuits work and talk to each other? I'm sure the connection between the left and right halves of the transmitter is wrong. Corrections and improvements gratefully received.
Thanks very much for your help.
Please could someone cast an experienced eye over the attached circuits? A raw beginner's attempt at combining (very) simple building blocks.
Here is the plan. To transmit a brief signal about 50 ft (15 m) when the temperature at the far end of my garden goes above 25 C, and to transmit another brief signal when it falls below 25 C. The 27 MHz crystal was chosen in order to stay away from the FM band, so not to disturb the neighbours' FM listening. The "brief" signal is to ensure that the toys in the neighbours' houses didn't wake up and get rowdy. Transmitter in the garden, receiver in my house.
For the transmitter, I tried to follow 27 MHz Transmitter | CircuitDiagram.Org. That circuit doesn't show where to attach V+ and GND, so I guessed.
For the toggle on the receiver, I tried to follow "Single MOSFET Toggle" from Circuits Page 9.
If it helps, here are the resistances for the B57891 10K 5% thermistor.
C ohms
24 10446
25 10000
26 9578
Using 2% resistors. I reckon the 560-ohm resistor will give about a 1-degree-Celsius window. And the temperature will go from 24 C to 26 C (or v.v.) in about a second. I'm aware of one fatal flaw -- where temperature goes from 23 to 25.1 and back to 23 -- but I'm willing to live with it, as a rare event.
The dual opamp's output will be "on" for probably no more than 30 seconds a day.
Anyhow, will these circuits work and talk to each other? I'm sure the connection between the left and right halves of the transmitter is wrong. Corrections and improvements gratefully received.
Thanks very much for your help.
