Echo/Tremolo Circuit for any electrical pickup out of a musical instrument PART

NO. 2212103

The kit is assembled in an aluminum box 2x3x5 in. with controls on top and runs on a 9V DC battery. The tremolo effect (echo) is

caused by a 555 timer that can be adjusted with two pots to obtain a variable output from an instrument such as a guitar or ukulele.

The circuit is standard but the effect is from a LED moderating a light dependent resistor CdS. It also uses a reed chopper if needed. The original Instructable can be found here: http://www.instructables.com/id/ECHO-TREMOLO-ELECTRONIC-EFFECT/

Time Required: 40 hours depending on experience Experience

Level: Intermediate

Required tools and parts: Soldering iron Pliers Saw Drill Screwdriver Plastic tube DVM

Bill of Materials:

Qty Jameco SKU Component Name

1 29066-1M R1-POT,LIN. TAPER,1M, .35 in.shaft.

Frequency control by operator while using the device.

1 29103 R2- Pot, lin. taper 100k

Frequency control, time base.

3 690865-1k R3, R4-R5 Resistor. 1/8w, 5%, 1k.

Current limiting resistors for the LEDs.R5 added for indicator if wanted.

1 135319-47Uf. C1- cap, aluminum electrolytic0.47uf, axial 63v.

Timing capacitor for 555 timer.

3 333489 L1,L2,L3 Led, T1-3/4,clear,80mcd@20mA

allt sup Jim-Pak BR5704J. Led.

Power indicator.

Optical vary of resistive unit of. Light variable resistor. L3 used for 555 timer output indicator if desired.

2 23077-T1-3/4 LH- Led holder T1-3/4.

Mount LED to chassis. For power on. Also used with 555output led indication. If desired.

1 202403 CdS-Light variable resistor

Cadmium sulfide 1/4in. dia. two leads. RS

has the spec on this item.

1 111448 Rel 1- Reed relay 6v, 250ohm.Normal open.

OMR-H on the side of relay. 4 pins used to vary the audio output by variable light from LED 1/2in. from it.

2 36311 d1, D2 diode 1N914 axial.

Sil-diode used to direct IC555 output into relay. and to prevent reverse emf of coil.[D2] type

DO-35

2 76241 SW-1, SW3, switch spst,toggle.

Turns on the 9vdc Vcc power to unit. Case side mounting also use as SW3.

1 318123 SW2- Switch,spdt,slide

Selects optical or Var res. method. low current. Use only once or twice intermittently depending on what is being tremmoloed.

Can be a toggle switch [used here]

1 76241 SW3-switch spst,

Can be a slide switch also. Used to cancel the tremolo effect and go to direct feed through of signal to be amplified. Can

be like the SW1 type. or toggle as used here.

2 2095437 J1, J2 , jack, 1/8 stereo case mount.

Stereo inputs and outputs. Use to feed signal audio into tremolo and out again. Using stereo plugs 3.5mm [1/8].

2 2161490 J3, J4, jacks, 1/8,momo.

Side mounting used to feed mono- plug signals in and out of tremolo circuits.

Two position, single, open.

1 526299 Sok-socket IC 8 pin. pc mount.

Low profile for pcb mtg. of IC 555. [IC1}

1 27422 IC1- timer 555. 600mw, 200ma, 18v.

The timer chops the input audio signal into time variable amplitudes. As a square wave input into the coil of the reed or if selected the Led which varies the CdS

resistor.

DIP-8,LM555CN

1 11280 Bat. 9v. clip electrical.

Clip connects to battery, two leads.

1 198731 Bat- 9v, alkaline,

Any 9v bat will work. Non rechargeable types.

1 2191891 Bat Mount clip

Mount to case. Use 42438Jameco, 6-32 screw as required.

1 11886 Case enclosure, aluminum, with screws.5-1/4x3x2-1/8

Two piece case. [enclosure]

5-1/4 x3 x 2-1/8

Case size will vary. Jameco size is slightly larger.

5x4x3 in H.

1 2191461 Board, grid style 356holes, 2 x 3.

Grid mtg bd. plated holes. Hard wired.

Jameco is 2x3.15 in.

PCB layout available.

1 639672-10Ft. wire awg 22 or equiv.

Wire can be discrete or flat cable wire stripped to size.

1 1581530 Clamp, circuit board.

Clamp was made of 10mil aluminum and mounted with 6-32 machine screws and nuts,

It is possible a mounting method ca be different from RS. Or use Jameco bracket:

.37x.25x.35Ht. using 4-40 screws {Jameco #106810 and nut 40943,1/2in. lg.

2 102788 knob

Transfer labels used here but Sharpie fine point also worked ok.

Step 1 - Observe Diagram of Project and Place Components.

Box for components-

The aluminum box is prepared as shown in the diagram. Optional item- Timer output indicator LED light that will vary in intensity and

on-off as the timing changes. An extra hole can be added to the enclosure top for the third LED, [Red] T-3/4 size. The hot lead is

connected to pin 3 of the IC555, other side to 1K to ground.

Step 2 - Circuit Diagram Explanation (see Fig. 1 on page 5)

1. Basic- The IC 555 is used to inject a pulse into the switches selected by switch S2 being optical switch or relay type switch. These

two switches open and close or change amplitude of the audio signal entering and leaving J1 to J4. Preamplifier In. and to Final

amplifier out. This causes the echo/ tremolo effect.

2. Optical switch- CdS [cadmium sulfide light sensitive resistor] and light source L2 LED. The IC555 output will control the LED via

the two pots. R1 and R2.

3. Relay switch- This relay operates from a coil and a reed relay.

The circuit is the same as the step 2. IC555 and pots. The output is chopped. A visual output is used by placing a LED in the output

of the IC555. [Optional].

Step 3 - Preparing a PC Board or a Bread Board

1 Place and solder the parts and extended wires. [11 wires].

2 Optical switch assembly is as shown. Place the LED#2 within 1/4 to 1/2 inch of the CdS resistor face. External light will be excluded

when the parts are covered by the aluminum cover. .

3 Relay - assembly is as shown. The two diodes D1 and D2 are used to aid the coil back-emf of the relay.

4 If a PCB is used- mount parts, solder. Attach a clamp to board to mount to aluminum cover. Use 6-32 machine screw.

5 Attach board and wires to aluminum lid as shown.

6 Attach Vcc 9vdc battery clip using 6-32 screw. Attach the two wired plug to the battery.

Step 4 - Prepare Aluminum Lid, Case and Parts.

1

2

3

The parts are switches 1, 2, and 3. Sw 1- power on off. Sw2- selector for type of output wanted - Optical or Relay. S3- Tremolo

in / no tremolo, only the input to output signal as amplified.

Pots R1 and R2 and Knobs to adjust the pulse width t1 and t2 for best performance. Frequency can be varied from 1 Hz to 20

Hz. with the two Pots.

Jacks, J1 and J2 are stereo plug in and J3 and J4 are Mono Plugins. J1, J3 are audio IN. J2, J4 are audio OUT. Optional- The

type of switches is not critical for the 3 shown. Slide switches can be used too.

Step 5 - Final assembly

1- Mounted PC or bread-bd. The clamp is made from a piece of .032 aluminum, dimensions as shown .The Bat clamp is as shown.

Mount the battery Last.

2- Connect all wires as shown to the pots, and switches. Routing of wires is not critical.

3- Mount the Pot knobs. Counter clockwise is marked with a pen as zero. Rotate clockwise to max. Mark as max. The half circle

can be divided into 5 intervals. Not critical.

4- Audio Tremolo is an on-off signal output that varies the audio of the mike or input. The Pots will vary this and you can experiment

with various settings to get slow or very fast tremolos.

5- Mount the cover and screw four screws as shown to top.

The top can be pre painted if one wishes before assembly of the switches. And pots.

6- Attach battery clips and wires. Turn on S1 power. LED L1 should light...

Note- The tremolo part can be silenced and the switch S3 can then be switched to out- and the system can be used as an amplified

output without tremolo.

Step 6 - Parts

1

2

3

4

5

6

7

8

9

Wiring - AWG 23 or parallel cable wires.

Switches- can be slide switches or as shown.

Pots- can be small size. Linear.

Resistors for LEDs 1/8 to 1/4W ±10 %.

LEDs. All LEDs are T1-3/4.bright red. Not critical.

Capacitor can be 0.47µf, 35v ±20%. Al-electrolytic. Or tantalum.

Jacks can be plastic box types.

Plugin relay- can be a 500 ohm coil.

The CdS resistor should read at least 300 ohms at fully lighted externally with a flashlight. The value is not too critical for operation,

however minimum lighting should be at least 200k value.