# transistor relay circuit

I'm confused about something.
I'm using the following relay: DSP1-DC5V
Originally I had 5-volts to the top side of a relay coil, the bottom side
to the collector of a 2N3904, the base is being driven by a 10k with 5- volts, and the emitter grounded.
I was unable to energize the coil, so I placed a 9-volt battery on the top side of the relay coil while still using 5 volts through 10k on the base and still was unable to energize the relay.
The datasheet states the relay coil is 83 ohms with a normal operating current of 60mA. If the transistor is on full, why wouldn't my 9-volt battery through the 83ohm relay coil energize when that is passing about 108mA through it?
Also, in this case, my collector current doesn't increase as I increase the base current. I thought the collector current would increase as I increase base current.
BTW, I'm working on a school project and I have all the circuits built and the only two circuits not working are my relay coils. I've spent most of the day on this problem and thought I could use x2 2n2904s but again, the base current doesn't drastically affect the collector currrent - all it does is decrease my beta ratio.
Any assistance would be appreciated.
Thanks in advance.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Peter wrote:

Diode + 9 -----------+---|<---+ | | [Relay] | | | +--------+ | /c +5 ---[1K]---| 2N3904 \e | Gnd -----------+
The diode is not needed to make the circuit work, it is needed to protect the transistor. Note the *1K* base resistor.
With good parts the above circuit will work, *provided the grounds from the 9V and 5V* *suppiles are connected together*
Ed
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

## Site Timeline

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.