UGH! I was obviously wrong when I thought I understood the way a Reed Relay (I guess any relay, in general) works. Or I have the setup horsed up!
I have been trying to get up to speed on a few different components for projects I am tossing around and I found a project online that, for the most part, was an exact match.
I will try to somehow get the circuit I tried attached to this thread, but it really seems so simple I must be missing something obvious.
9V Supply
100k R
Photoresistor
2N4401
Reed Relay
The R1 and Photoresistor in series (Voltage Divider Set-up Right?)feeding the base pin of the 4401. When lit, the transistor is "off".
When dark, the V across base increases and triggers the transistor. I started with a simple LED circuit connected through the collector/emitter to see if I had the transistor pins understood. Worked like a champ. Light source on - LED off. Light source off - LED on. Hurray!
I thought I could set the same exact LED test circuit up - through the relay. Intead of directly turning on the LED, I thought the transistor would trigger the relay connection - thus completing the LED circuit.
So, a few questions about this experience.
1. When using a transistor, is the circuit "dead" whenever the base pin is not receiving the necessary trigger voltage? Meaning, you cannot set up a LED indictor using the Emitter pin to show the condition of the "base"?
2. I thought it would be easy to find, but no luck. Can someone just confirm the pins of a reed relay. Which pins "close" the other pins?
3. General question about relays - the circuit that activates the relay is separate that the circuit completed by the relay? The completed circuit may be sig. different (as long as within the relays specs) than the activating circuit?
I know these are probably very simple concepts, but I want to make sure I get corrected if my non-technical understanding is off base.
Thanks - help any way you can. I know it is very difficult with out the exact circuit I tried - I will work on getting it added here.
Steve
I have been trying to get up to speed on a few different components for projects I am tossing around and I found a project online that, for the most part, was an exact match.
I will try to somehow get the circuit I tried attached to this thread, but it really seems so simple I must be missing something obvious.
9V Supply
100k R
Photoresistor
2N4401
Reed Relay
The R1 and Photoresistor in series (Voltage Divider Set-up Right?)feeding the base pin of the 4401. When lit, the transistor is "off".
When dark, the V across base increases and triggers the transistor. I started with a simple LED circuit connected through the collector/emitter to see if I had the transistor pins understood. Worked like a champ. Light source on - LED off. Light source off - LED on. Hurray!
I thought I could set the same exact LED test circuit up - through the relay. Intead of directly turning on the LED, I thought the transistor would trigger the relay connection - thus completing the LED circuit.
So, a few questions about this experience.
1. When using a transistor, is the circuit "dead" whenever the base pin is not receiving the necessary trigger voltage? Meaning, you cannot set up a LED indictor using the Emitter pin to show the condition of the "base"?
2. I thought it would be easy to find, but no luck. Can someone just confirm the pins of a reed relay. Which pins "close" the other pins?
3. General question about relays - the circuit that activates the relay is separate that the circuit completed by the relay? The completed circuit may be sig. different (as long as within the relays specs) than the activating circuit?
I know these are probably very simple concepts, but I want to make sure I get corrected if my non-technical understanding is off base.
Thanks - help any way you can. I know it is very difficult with out the exact circuit I tried - I will work on getting it added here.
Steve