delabs Circuits

Thursday, September 18, 2014

Up-Down counter-timer

(A question answer thread of delabs.net, nearly a decade old)

Presettable Up-Down counter-timer-Question   

I am looking for a schematic for a pre settable Up/Down counter that I can build for my church. It needs to be 5 decades. From 0:00:00 to 9:59:59. I ran across your web pages while searching for such a schematic. Can you help me out?

EE



Presettable Up-Down counter-timer-Answer

It appears from the "9:59:59 " you have mentioned, what you need is a timer.It it a count up and count down timer you need, like a clock ?

Can you explain to me how you plan to use this circuit in the church.Visit the links below and see if that is what you want.

delabs


Presettable Up-Down counter-timer-Reply 

Thanks for the links. What I need this count down timer for is to allow speakers at the church to know how much time is remaining of their presentation. All of our speakers are taped for later use or review. The speakers giving the presentation usually go over their time limits for the audio tapes. With this unit I am trying to build time can be entered by preset thumbwheel switches. The counter is then started and times out when the counter reaches 0:00:00.

What makes this count down timer different is there will be two seperate displays. A one inch set of seven segment LED's will be in the main console with the rest of the logic. There will also be a 2.5 inch set of seven segment displays remotely connected (anout 3 feet away). The large displays will be what the speakers will see. The small displays will be in the control booth.

I already have the following items gathered up. I am hoping to use these components if I am able. I have the MC14029, the MC14513, the Allegro UDN2597A (to drive the large LED's), the Dallas Semi DS32KHz time base, the MC14020, the MC14013, the large and small LED displays, and the thumbwheel switches (set to 9:59:59 maximum)

I also have some MC14011, MC14490 (Hex Debounce Switch Controller, MC14049, and the R's and C's necessary to complete the circuit.

Does this explain what I am trying to do? I think the MC14029 counters can be used to do all the counting and store the preset values. All I have to do is add the reset at 6 for the tens of seconds and the tens of minutes. However, I don't know how to connect the logic?

The DS32KHz, MC14020 and MC14013 will generate the 1 Hertz (1PPS) signal. That is about all I currently have. That is why I need some help

EE


Presettable Up-Down counter-timer-Answer

below are two circuits in pdf format see if they are ok see... Digital Circuits-2

Circuit 1 - Digital Timer Clock With Preset using Thumbwheel switch.


Circuit 2 - 1 Hz or 1 pps crystal clock using CD4060 and 32768 Hz Crystal.


They have not been tested much... The 4513 control pins 8-4-5-3 connections verify, as i did not get the datasheet.

the circuits will work as concepts are right, but some tweaks in R C values may be required.
the R C values can only be corrected if you have problem in making it work.

the main problem in the R C values may be related to "the reset at 6 for the tens of seconds and the tens of minutes". tell me what changes you may want. this is a presettable count down timer upto 99.59.59 hours.minutes.seconds

delabs

Wednesday, September 17, 2014

Temperature Meters with Analog Recorder Output

I would like to know if you offer a monitoring solution that will constantly measure ambient (air) temperature (say, 0 to 150°F), and provide a corresponding DC voltage output of either 100 mV, 1 V, 5 V, or 10 V. Do you make a unit that can be configured to do this?

Mail From JPE - WV - US


Analog outputs were very popular as they are inputs to Strip Chart Recorders, Later they had an extra use for PC Based Data Acquisition, data Loggers and PLC. Now we have Instruments with digital and wireless outputs too.

Temperature Meters - DP116 - Omega
 
Economical 3/64 DIN panel meter that has a full size 0.56" green or red LED display, with a built-in analog output and display hold capability. 3 1 /2 Digit Display.

Features Include
  • Thermocouple and RTD Input
  • Full-Size 0.56" (14.2 mm) LED Display
  • Analog Output Standard
  • 1 /8 DIN Panel Adaptor Standard

Economical Digital Meters DP18 - Omega

Economical Digital Meters DP18 - Omega

The DP18 series is a complete family of panel meters with input cards for voltage, process and temperature measurement and control. The signal conditioners for voltage will measure ac or dc voltages or true RMS.

Modular Design, Options for Alarms, Analog Output of Communications, 3 1/2-Digit LED Available in Red or Green Displays

delabs

Friday, September 12, 2014

Noise and Hum in Audio Circuits

"I currently have a car stereo set that i use as an amplifier in my living room. but my main problem is that i a lot of noise hum when ever it is on especially when there happens to be a drop in the supply Voltage. i decided to use a voltage regulator and capacitor across (1600uF)...but it only reduced the hum a little. how can i completely eliminate the noise". - Question  by FP

Answer by delabs 

Ensure that the power supply has a full wave or bridge rectifier. If power supply transformer is say 12-0-12 two diodes must be there and a center tap ground OR If a square or round bridge is used with four leads or four diodes, then it is fine. Half wave rectification or a blown or leaky diode can cause this problem. Put all the filter caps you want and add a series choke as well the better the power supply the audio will be good.

Noise and Hum in Audio Circuits

The power supply transformer rating - voltage and current both may need to be boosted. Some very low budget transformers do not use CR-GO plates for lamination (i think it is Cold Rolled Grain Oriented ). They use plain thick metal plates without coating and hence hysteresis and eddy current both cause problems. Then you have ground loop hum and noise of semiconductors, the speaker ground and amplifier ground carry current and they should be directly connected to power supply ground, These you can understand by looking at these pages......

I am only aware of Phillips transistor based designs used 20 years back, but these have more...

Noise in Audio Amplifiers

"Noise has enormous nuisance value with sensitive (i.e. high gain) circuits, but the information provided by most IC and transistor makers.."

Avoiding Ground Loop Hum

"To solve the problem, the goal is to reduce the magnitude of the loop current. This is done simply by inserting isolation resistor(s) in series with the audio cable ground(s)..."

Audio, Power, and Control Lines

"The correct place for an audio ground is at the microphone connector entrance to the shield enclosure of the radio..."