Street Organ Help

[windmillnut]

Hello,
I am looking to build my own version of a crank street organ. You know the kind with the guy and a monkey.

I plan on mounting a car stereo, speaker, and battery in a cabinet and rig it so that the radio plays either when someone is turning the crank or without if a switch is flipped.

The setup of the radio, battery, and speaker I think I can handle. What I cannot figure out is how to design a cadence detector to only allow the radio to play the music if someone is turning the handle. Does anyone know of someone that would design the circuit for my project for a fee? I only need one so to ask a big design firm to do it seem silly.

Any help would be appreciated.

[KMoffett]

Are you thinking of switching on/off power to the radio, or just cutting out the speaker with the "crank" circuit. Cutting power to the radio my not have the radio automatically turned-on when power is reapplied. I can see a simple "missing pulse detector" circuit connected to the crank to detect if the crank is being turned above a minimum rate. This would switch a relay or solid state component to turn on and off the power or speaker.

Can't help with the monkey!

Ken

[KMoffett]

The attached is a simple missing pulse detector I've used. SW1 is a switch that would be pulsed on and off by the rotation of the crank. The mechanism would be determined by your mechanical design. If the switch is repeatedly pushed and released more often than once a second the relay will be turned on, and stay on. As soon as the switch rate drops below 1/sec or stops the relay will drop out. The 1/sec is just what I happen to have used in this circuit. It could be adjusted by changing R2 and/or C1.

A latching ON/OFF switch could be added in parallel with SW1 to maintain the relay on, bypassing the need to crank.

Ken

[windmillnut]

Ken,
Thank you very much for the layout. I stopped off at Radio Shack on the way home from work and picked up a few things.

Lever Switch 5aA at 125/250 AC
100k 1/2 watt carbon film resistors
1k 1/2 watt carbon film resistors
4.7uF Electrolytic Capacitor non polarized
1N4148 switching diode
SPST-12VDC Reed Relay .5A at 125VAC
and a mini lamp for testing 12volts 25mA

I still need to find the transistor 2N7000.

I never put together a circuit before so here come the questions.
Are the 1/2 watt resistors the right size they also had 1 watt resistors.
I have not purchased a on off switch yet. What should it be rated for?
What gauge wire do you recommend between the lever switch, on off switch and the rest of the components which will be mounted to a perfboard which I also purchased.
Also the lever switch has three connectors one of which I imagine is a ground. The circuit will be in a wooden cabinet so I have no way to ground it.
Also the relay I purchased has four connections. Two coil, a com and a N.O. I imagine the connections are made between the com and NO pins.

Thanks for you help!
Brian

[KMoffett]

I still need to find the transistor 2N7000.
This should work OK:http://www.radioshack.com/mosfet-irf510-transistor/2762072.html#q=MOSFET&start=1
I never put together a circuit before so here come the questions.
Are the 1/2 watt resistors the right size they also had 1 watt resistors.
Yes.
I have not purchased a on off switch yet. What should it be rated for?
It can be any switch (maybe not tactile) as this is very low voltage and current.
What gauge wire do you recommend between the lever switch, on off switch and the rest of the components which will be mounted to a perfboard which I also purchased.
Small wire. Again, this is very low voltage and current.
Also the lever switch has three connectors one of which I imagine is a ground. The circuit will be in a wooden cabinet so I have no way to ground it.
The switch has a Common, a Normally Open, and a Normally Closed contacts. You will use the Com. and N.O. connections. No ground.
Also the relay I purchased has four connections. Two coil, a com and a N.O. I imagine the connections are made between the com and NO pins.
Yes. The Com. and N.O. will switch whatever you decided to switch. However, if you decide to switch the radio power supply, that relay's contacts will not handle the current. If you decide to switch the speaker, some amplifiers do not like to work (think smoke) with no speaker load connected.

The timing determined by the R2 and/or C1 may need to be changed to meet your particular need. Doubling the value of R2 doubles the maximum time the relay remains on between input pulses (SW1). Halving the value cuts the time on half. The same goes for C1.

Ken

[windmillnut]

I am back from a trip to Radio Shack. I picked up a 12VDC Auto Relay SPST 30/40A, a spst mini toggle siwtch(10A at 126 VAC), and a IRF510 MOSFET transistor n-channel 60 volt).

I taped them all to a piece of paper to work out what I have to solder to what and of course I am troubled.
The first thing is the capacitor I had purchased indicates that it is a non-polarized capacitor while the diagram indicates a polarized one. I noticed the little plus sign.

I took a few pictures:
Shown is the trigger switch and the on off switch.

007-2.jpg (5.03 KiB) Viewed 93184 times

This shows the resistors, capacitor, and the transistor. I think my hook up of the transistor is wrong!

008-2.jpg (4 KiB) Viewed 93184 times

This shows the diode and the auto relay. Wires will go to terminals 30 and 47

011-2.jpg (4.24 KiB) Viewed 93184 times

[KMoffett]

The non-polarized capacitor is OK. There some problems with the MOSFET and relay connections.
I did a quick Paint diagram of the correct connections. Sorry about the drawing quality. Pins 87 and 30 are used to switch whatever you intent to turn on/off.

Ken

[windmillnut]

Thank you for the picture it helped. I am going out to Radio Shack again. Trip number three. What type and gauge of wire should I use for the circuit? I have 22 gauge solid wire now. This circuit will be connected to a 12 volt car battery. What type of wire should be used between the car battery and this circuit. Also do you have a suggestion as to the power connectors to use between the battery and the circuit board and also between the relay and the radio?

Thanks again for your help. This project of mine would not get off the ground without it. I will draw up the diagram with pictures of the components to get an OK before I start to solder.

Brian

[KMoffett]

22Ga wire is OK for connecting the battery to my circuit...and on the board. Are you going to switch the radio power or the speaker? If the radio, how much current does it draw?

I looked at your original post. If you are going to have two speakers and switch them, you are going to need a different relay like one of these: [url]http://www.radioshack.com/compare?category=0006-0004-0013
[/url]

Ken

[windmillnut]

Well I did not tell the whole truth last night. In addition to going to Radio Shack I also stopped off at Best Buy and pushed some buttons and turned some dials. My intention is to cut the power to the stereo.

I have decided on this receiver.
http://www.bestbuy.com/site/pioneer-cd-car-stereo-receiver/6238551.p?id=1218723188595&skuId=6238551

As far as speakers are concerned.
http://www.bestbuy.com/site/pioneer-6-1-2-2-way-car-speakers-with-impp-composite-cones-pair/8063063.p?id=1219309058439&skuId=8063063

Now these have been selected by speaking with the floor staff.
My biggest concern with the stereo and speaker selection is that the stereo must be able to pick a song up from where it left off after I cut the power to the stereo when I stop cranking.
Also the stereo must be able to run for about 8 hours from a standard car battery so it must be efficient.
The speakers must be able to reproduce the following type of music in a realistic manner. That is NOT me in the video.
http://www.youtube.com/watch?v=SDl2ooWFWhA


Needless to say I should speak with a stereo installer to get their opinion. I may end up purchasing a completely different combination, but the above are the front runners.

Brian

[KMoffett]

Sorry, can't help on any of that. Are you sure you need that much power. Lots of power over a long time means a big heavy battery.

Ken

[KMoffett]

Another thought...I think on auto radios cutting the power may dump their internal memories: clock, radio presets, CD vs radio, CD track. If you want to start and stop with the same function/song you will need to investigate that.

Ken

[windmillnut]

Ken,
About the radio losing all power and losing all of its settings, I was kind of ignoring that elephant in the room for the time being. If after speaking with a radio tech it cannot be done and the elephant will not leave the room I will have to turn off power to the speakers instead. In a prior post you mentioned a relay to turn off the speakers. I followed the link but it just brought me to a comparison screen with no items on it.

I will find a radio tech here in Green Bay and get their opinion so I know which way to go from here in regards to the radio and speaker setup.

Thanks,
Brian

[KMoffett]

The radio shack link was to show two options for 12V DPDT relays for the speakers:
http://www.radioshack.com/12vdc-coil-dpdt-miniature-pc-relay/2750249.html#prefn1=productType&prefv1=DPDT&start=3
http://www.radioshack.com/12vdc-3a-dpdt-plug-in-relay-and-socket/2750206.html#start=15&sz=12

If you find a radio tech, ask if the radio can run OK with the speakers disconnected, otherwise dummy load resistors will also need to be added to the relay.

Ken

[windmillnut]

Well I wired up circuit. It looks pretty good for a mad scientist. I have a question about the power source. I did something I should not have done I guess. I took a 12 volt lighted switch and a car turn signal light and connected them to a car battery. I fried the stranded wire that I used to create the circuit to test just the light!

With any luck the blue smoke will settle in the basement before the wife notices.

I have not powered up the circuit I made. I will post some pictures once my camera gets recharged.

In order to test the circuit what power source should I use? I wanted to use the car battery I am going to power the radio with. I fried the 18 gauge stranded wire I intended to use so I wonder if a lower gauge single conductor wire would have been better.