a few ???

Discussion in 'General Electronics Chat' started by Mathematics!, May 11, 2009.

  1. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    Question 1

    I have bought 2 types of solder boards from radioshack.

    One has copper rings around the wholes the other does not.

    When I solder on the copper ring one the solder melts to the board and to the component leg.

    But when I use the non copper ring board the solder only melts to the component leg. Is their anything I can get to make the solder melt to the board and the component leg? The non copper ring boards at radioshack cost alot less.
    Do you need special chemicals to use these?

    Question 2

    I have a 8 ohm, 2 watt speaker. I also had an LM386 amplifier. I am wondering if I can use these 2 components with a microphone to hear my voice out of the speaker? Note I have computed the current from the 2watt power and 8 ohm resistance. Is this current the current that would create the sound provided I use enough capacitors to get it in the 20HZ 20kHz range. (hearing range)

    Question 3

    Why , when the phone is off the hook nobody can make a phone call to you. I would think the circuit is complete when the phone is off the hook.
    And the phone circuit is not complete when the phone is on the hook.
    Also this leads to the question of why the phone rings AC 90 volts 20 Hz if the phone circuit is not complete?
  2. bertus


    Apr 5, 2008

    I have some possible answers:
    Question 2:
    It depends on what kind of mic you want to use.
    The output of the mic may be to low to drive the LM386 direct.
    You will need propably a preamp between mic and LM386.
    Here are some links to mic preamps:

    Question 3:
    Take a look ath the link about signals and circuits for telephones:

  3. Fenris

    Active Member

    Oct 21, 2007
    It sounds like you have 'perf board' the copperless sheet. You have to use wire the join everything together. The same goes for the copper ringed board.

    Heres a circuit I use with the LM386. There are loads of variations though. I built this just this week it works well. Please note I fitted the Volume pot on the track side of the board to get the correct 'sense' IE CW increase volume CCW decreases volume. If mounted on the component side it was reversed and also lost some range. You also need a pre-amp so that the LM386 will work with the mic. See also the LM358 circuit picture.

    As for the third........ I know not.


  4. Externet

    AAC Fanatic!

    Nov 29, 2005
    There is two circuits inside your telephone
    - The voice circuit is disconnected from the line when handset is on the craddle
    -The ring circuit is connected to the line when the handset is on the craddle.
  5. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    But their is really only the green and red wire being used on the telephone line. So inside the phone does the green and red wires split into 4 wires?

    Because I don't see how the circuit goes. Is it only the ring circuit and the voice circuit or are their more circuit inside the phone.

    Is the ring circuit only complete when the phone is on the line and it's only purpose is to make the phone ring?

    And when the phone is off the hook the voice circuit is closed and the ring circuit is open?

    But I still don't get why people cann't call you if the phone is not on the hook. You would still have the voice circuit complete?

    Yes, but for the 'perf board' without copper rings , it seems to be impossible to get the solder to stick to the board and the component legs.
    What I mean is I can solder components together but the back of the components legs don't seem to stick to the board only to each other.
    I thought on these boards the components should stick to the board as well as the legs.

    When I use the copper ring ones the legs of the components stick to the board as well as each other when soldering.

    I am just wondering if their is some special substance I need to beable to get the solder to stick to the board as well. Something copper chemical or something? Note I never soldered with flux maybe this is the reason?
  6. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    The perf board without copper rings is not going to act like perf board with copper rings. Your components and solder stick to the copper rings and not the board itself. The copper rings are connected to the board. That is the only connection. That is why the boards with the rings are more expensive. They make the work much easier to do.

    Flux will help you solder components and wires to the existing copper rings.

    I think you will have the same trouble with any "copper chemical or something" that you put on the board to connect the parts. What will make it stick to the board? You need some sort of adhesive.

    As for the phone calls while you are off hook ...

    When the phone is on hook, on the base, the phone draws no current in the loop and the ringing circuit is visible to the phone company. When you pick up the phone, the phone goes off hook, and your voice circuit is placed on the line and the ringing circuit is removed. In this configuratioin, there is current flowing constantly through your phone. The phone company sees this loop current they consider your phone "busy" and they do not attempt to place another call on the line.
  7. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    Ok, I get what you are saying but I am wondering about people that have 3 way conversations ...etc. You have to pay extra but some how the switch at the phone company will connect more then 2 people. I don't really know why it cost more it is basically just connecting more people which is nothing more then connecting more switches together. Maybe they use special switches for those people that have 3 way conversations aside from the regular switch?

    When the phone is off the hook the phone companies switch detects the voice circuit is complete and assumes the line is busy. But then why do you get a beep if a second person calls while you are already on the line. Shouldn't he get a busy signal same as the case when the phone is off the hook?

    I believe the ring circuit is complete when the phone is on the hook but their is a diode that doesn't allow any current until the AC is put down the line from the phone company's switch. Thus making it look as if it is an open circuit but it will be only open for DC not for AC. Half the AC cycle will generate current down the ring circuit line. ( I.E when the diode is in forward bais )

    As for the perfboard with no copper rings. What good are they for if you cann't get the components to stick together on the board.
    I am curious if anybody uses these and what they do to make the components stick to the board?
    Why do they even sell them.

    They also sell , like nondrilled to boards but I would think these would have the same problem?

    Their must be some kind of substance you can use to make them stick to the board?
    Last edited: May 12, 2009
  8. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    You have to pay more for a three way call because you are using more of the phone companies equipment, which they must pay for as equipment cost, maintenance, and personel, ... That is how the phone company makes money.

    As for the "call waiting" beep you get when you are on the line, that is another service that you pay for. So, they let you have the feature. If you do not pay you do not get it.

    The phone company is notified when someone wants to call you.
    They check your line to see if it is busy.
    If not busy, they will ring your phone.
    If it is busy, they send the call waiting beep to your phone.