Since there seems to be a lot of interest in building an Electronic E-Caller I think this post will save some time in the long run. To start with I am no expert, but have been building E-Callers for the better part of 10 years. OK so maybe I am too cheap to buy one, but to be totally honest I guess I have yet to find one with all the features I want in a pre-made Caller. For the first several years I would build one, use it and then as I was using it I would figure out a way to make it better. For the most part this meant more compact. Sonce of the ones I have built were from ideas shared by guys that also enjoy putting these types of callers together, while other ideas were out of despiration to make the units more compact. I have used Cassettes, CD's, and finally MP3 Players for the sound source (and yes even used one of the Boom Boxes a time or two).
To start with you'll need an Amp. I have found the little Radio Shack Amp (part #277-1008 = $12.99). I have experimented with this and other amps and dollar for dollar this little amp works, provides all the needed volume for about 90% of the calling you'll ever need, and the 9 Volt transistor Battery seems to last forever (provided it is not left on when not in use for days on end).
This little Radio Shack Amp actually is in a small plastic housing and there is a little 2" speaker inside the housing. The first thing I do is to remove the amp circuit board from the original housing. Next (through trial and error) I find the sweet spot on the volume control (on off switch volume control) at which the volume does not get any louder by turning the volume past that point, but rather just increases amp hiss/noise. I then remove the volume wheel from the volume control and hot glue the volume control in a fixed position.
Since we have disabled the On-Off Switch on the amp, we need to wire in a separate On-Off Switch (Radio Shack #275-1565 = $2.59 ea). I also like to wire in a small LED Indicator Light to help in not leaving the Amp turned on when not in use (Radio Shack #276-084 - $1.99 ea). One wire from the LED Indicator Light and the Red Wire from the Amp Circuit Board get soldered to on terminal on the On-Off Switch.
The positive lead from the new 9Volt Battery Connector (Radio Shack #270-325 = $1.99 per pck of 5) gets wired to the other terminal of the On Off Switch. The negative wires from the new Battery Connector, Amp Circuit Board and LED Indicator Light all get soldered together.
That is about it for wiring. Depending on how or what you choose to mount your amp in (I use either a Radio Shack Project Enclosure #270-1805 = $3.79 or an insulated Coffee Mug) you may or may not need a couple of 90 degree adaptors (Radio Shack #274-372 = $3.99 each. The 90 Degree Adaptors are needed for clearance to get the speaker and patch cord (that goes between the amp and the sound source) plugged in inside of the coffee mug.
Next is the patch cord to go between the Amp and the Sound Source (Radio Shack #42-2497 1' patch cord with 1/8" Stereo Plugs on each end = $4.29) and the sound source. You can get a premade 6' patch cord also if you need to have the sound source farther away from the amp.
Radio Shack items parts list
Radio Shack #277-1008, Mini Audio Amplifier/Speaker = $12.99ea
Radio Shack #275-1565, SPST Soft Feel Push on Push Off Switch = $2.59ea
Radio Shack #276-084, LED Indicator Light for Amp (fits 3/16" hole) = $1.99ea
Radio Shack #42-2387, 6 Foot Patch Cord 1/8" Stereo Plug on each end = $4.99ea
Radio Shack #270-325, 9V Snap Type Battery Connectors (Pkg. of 5) = $1.99ea
Radio Shack #270-1805, Project Enclosure ((6"x3'X2") = $3.79ea
The speaker I have found to produce the absolute BEST sound is the Speco SPC-5 PA Speaker. These can be order online from Lashen Electronics, they are $8.42 plus shipping, but they have a minimum order of $25.00. This speaker comes with about 10 feet of speaker wire and a plug attached (or at least the ones I have used have) to plug the speaker directly into the Speaker Jack on the Radio Shack Mini Amp.
On to the sound source. Your imagination and what you are willing to spend will limit your choices. Some of the guys are using some of the new I-Pods, while others are using MP3 Players and yet others digital voice recorders. I have had good luck with the Rio 600 MP3 Players, and if I had a complaint it is the small buttons and readout screen (I can not read the track titles without my glasses).
Now for you guys that have asked about WIRELESS, yes this too can be done. I have put together a couple WIRELESS Callers, but quite honestly I haven't used one all that much as I figured it was just more batteries to go dead when least expected. It is a simple matter of using a Cam Corder Wireless Mic Transmitter and Receiver to make this E-Caller Wireless. From what I have read elsewhere the AZDEN WLX-PRO Wireless Mic System is one of the better ones, and the ones I have used. These are a two channel system so if you get interference on one channel, try the other one as it may provide clearer sound.
It is a simple matter of plugging the MP3 Player into the Wireless Transmitter. With the Azden you'll need a 6 Foot Patch Cord to go between the MP3 Player and the Azden Transmitter as this cord acts as the antenna for the Transmitter. The Receiver gets plugged into the INPUT on the Amp and the Speaker stays plugged into the OUTPUT on the Amp.
Yep it is as simple as that.
Below are a few photos of a couple of callers I have built.
I am sure I have left something out, and if so just ask away.
Larry
To start with you'll need an Amp. I have found the little Radio Shack Amp (part #277-1008 = $12.99). I have experimented with this and other amps and dollar for dollar this little amp works, provides all the needed volume for about 90% of the calling you'll ever need, and the 9 Volt transistor Battery seems to last forever (provided it is not left on when not in use for days on end).
This little Radio Shack Amp actually is in a small plastic housing and there is a little 2" speaker inside the housing. The first thing I do is to remove the amp circuit board from the original housing. Next (through trial and error) I find the sweet spot on the volume control (on off switch volume control) at which the volume does not get any louder by turning the volume past that point, but rather just increases amp hiss/noise. I then remove the volume wheel from the volume control and hot glue the volume control in a fixed position.
Since we have disabled the On-Off Switch on the amp, we need to wire in a separate On-Off Switch (Radio Shack #275-1565 = $2.59 ea). I also like to wire in a small LED Indicator Light to help in not leaving the Amp turned on when not in use (Radio Shack #276-084 - $1.99 ea). One wire from the LED Indicator Light and the Red Wire from the Amp Circuit Board get soldered to on terminal on the On-Off Switch.
The positive lead from the new 9Volt Battery Connector (Radio Shack #270-325 = $1.99 per pck of 5) gets wired to the other terminal of the On Off Switch. The negative wires from the new Battery Connector, Amp Circuit Board and LED Indicator Light all get soldered together.
That is about it for wiring. Depending on how or what you choose to mount your amp in (I use either a Radio Shack Project Enclosure #270-1805 = $3.79 or an insulated Coffee Mug) you may or may not need a couple of 90 degree adaptors (Radio Shack #274-372 = $3.99 each. The 90 Degree Adaptors are needed for clearance to get the speaker and patch cord (that goes between the amp and the sound source) plugged in inside of the coffee mug.
Next is the patch cord to go between the Amp and the Sound Source (Radio Shack #42-2497 1' patch cord with 1/8" Stereo Plugs on each end = $4.29) and the sound source. You can get a premade 6' patch cord also if you need to have the sound source farther away from the amp.
Radio Shack items parts list
Radio Shack #277-1008, Mini Audio Amplifier/Speaker = $12.99ea
Radio Shack #275-1565, SPST Soft Feel Push on Push Off Switch = $2.59ea
Radio Shack #276-084, LED Indicator Light for Amp (fits 3/16" hole) = $1.99ea
Radio Shack #42-2387, 6 Foot Patch Cord 1/8" Stereo Plug on each end = $4.99ea
Radio Shack #270-325, 9V Snap Type Battery Connectors (Pkg. of 5) = $1.99ea
Radio Shack #270-1805, Project Enclosure ((6"x3'X2") = $3.79ea
The speaker I have found to produce the absolute BEST sound is the Speco SPC-5 PA Speaker. These can be order online from Lashen Electronics, they are $8.42 plus shipping, but they have a minimum order of $25.00. This speaker comes with about 10 feet of speaker wire and a plug attached (or at least the ones I have used have) to plug the speaker directly into the Speaker Jack on the Radio Shack Mini Amp.
On to the sound source. Your imagination and what you are willing to spend will limit your choices. Some of the guys are using some of the new I-Pods, while others are using MP3 Players and yet others digital voice recorders. I have had good luck with the Rio 600 MP3 Players, and if I had a complaint it is the small buttons and readout screen (I can not read the track titles without my glasses).
Now for you guys that have asked about WIRELESS, yes this too can be done. I have put together a couple WIRELESS Callers, but quite honestly I haven't used one all that much as I figured it was just more batteries to go dead when least expected. It is a simple matter of using a Cam Corder Wireless Mic Transmitter and Receiver to make this E-Caller Wireless. From what I have read elsewhere the AZDEN WLX-PRO Wireless Mic System is one of the better ones, and the ones I have used. These are a two channel system so if you get interference on one channel, try the other one as it may provide clearer sound.
It is a simple matter of plugging the MP3 Player into the Wireless Transmitter. With the Azden you'll need a 6 Foot Patch Cord to go between the MP3 Player and the Azden Transmitter as this cord acts as the antenna for the Transmitter. The Receiver gets plugged into the INPUT on the Amp and the Speaker stays plugged into the OUTPUT on the Amp.
Yep it is as simple as that.
Below are a few photos of a couple of callers I have built.
I am sure I have left something out, and if so just ask away.
Larry